Let’s Not Confuse Capability With Capacity

That sentence above is one that pops into my mind often - both to remind myself and, also, in the therapy room.

Because they DO often get confused. I don’t mean that I see definitions, spellings or context getting mixed up. What I do see though is people assuming that one directly relates to what it means about the other - and what that then means about themself. Followed by a self-criticism (said out loud or otherwise) that is both unfair, and inaccurate.

There is a big difference between capability and capacity. And there are also other systems at play which directly add to the self critical narrative and our responses to them.

let’s start with some definitions:

Capability is what you are able to do. Your skills, your knowledge, your competence.
Capacity is how much you have available to give - and includes what you have available alongside everything else that's going on.
That last bit there matters.

You might be completely capable of something and have absolutely no capacity for it. And you may have lots of capacity but not be the person for the job in hand (i.e. someone else is more capable). These are not the same thing, and one does not cancel out the other.

For Example: That day when its just not happening…

You might know this feeling: You sit down to do something you've done a hundred times before — write the email, have the conversation, finish the task — and it just won't come. It feels harder than it should and you can’t understand why.

The mind chatter starts to make a story: Why can't I do this? I've done it before. I should be able to.
You berate yourself. You maybe try even harder, or push through determined to do what you should be able to do and to the standard that you should be able to do it. ‘Should’ is doing a lot of work in that sentence and holding you to the standard of you that has more resource than you have that day. The self criticism is basing itself on a version of you that has had more sleep, more space or hasn’t had to deal with all the emotional stuff going on elsewhere or the overwhelm that has been building up.

That's not a capability problem. That's a capacity problem. And just because you don’t have capacity, it doesn’t now mean that you're not capable.

Another Example: The diary that looked fine

The other version of this I see often goes something like this. Someone looks at their schedule, sees a gap, knows they're capable of whatever is being asked, and says yes. They have the skill, they have the time slot, it makes sense. Of course they say yes — why wouldn't they? (Let’s just also sneak in a little side point that we might pick up on another time: they might not want to do the thing)

What they haven't accounted for is everything else. The emotional weight of a difficult week. The mental load of three ongoing situations that aren't yet resolved. The social tiredness from too much people contact and not enough solitude. The fact that their nervous system is already full, even if their diary isn't.

And so when the commitment arrives, they either cancel — and most probably feel guilty about it — or they push through and feel resentful, exhausted, or hollow afterwards. Neither outcome feels good. And the mind chatter creates a story that is most likely something negatively about how they are as a person, or how they compares to others: Why do other people seem to manage? Why do I do this all the time? What’s wrong with me?

Often, people pleasing or perfectionism sits underneath this. There’s a feeling that saying yes because you’re capable of doing something is the ‘right’ thing to do or that it’s what ‘capable people’ do.

But it’s not the whole story when we ignore what our capacity is in a fuller sense beyond checking our diary to see if we have time.

We have different kinds of capacity

Capacity is multi-dimensional. It’s our energy levels across different areas:

Physical capacity. Mental capacity. Emotional capacity. Screen capacity. People capacity. There’s the capacity to absorb more information or stimulation and the capacity to be present with another person without it costing more than you already have to give. And probably many many more that I can’t bring to mind right now (and no doubt will after this!)

These don't all run low at the same rate, and they don't all replenish in the same way. Running on empty in one area affects all the others. and when we don’t realise it, it it can lead to that self criticism and feelings of being ‘less than’ in some way.

There’s a shame that doesn't belong here

I want to be really honest here: so many of us are walking around believing we're not capable of things we are entirely capable of. And in actual fact we've ‘simply’ run out of capacity and then drawn the wrong conclusion about ourselves.

And on the other side, so many of us are consistently overstretching ourselves — saying yes beyond what we actually have to give, or want to give — and then feeling like we're failing or letting people down when really we're just human.

Neither of these are character flaws.

I think it's also important to zoom out for a moment.

Because this confusion between capability and capacity doesn't just happen inside individual minds. We live in systems that constantly encourage us to do more, be more, achieve more and optimise more. We are surrounded by messages that suggest there is always another habit to build, another area to improve, another way to become a better version of ourselves.

Social media algorithms are designed to keep our attention. Marketing often relies on highlighting what we lack before offering a solution. Many of the structures around us benefit when we believe the problem lives entirely within us and that fixing it is our individual responsibility.

And then there's the comparison layer on top of all of it. When we're already being hard on ourselves, it's very easy to look outward — at colleagues, friends, or the curated version of people's lives on social media — and conclude that everyone else is managing just fine. That they're doing all the things, keeping all the plates spinning, and somehow finding it effortless. Why can't I do what they're doing?

But what we're not seeing is what's happening behind the scenes for that person. We're not seeing their overwhelm, their resentment, the things they cancelled, the sleep they lost, or the quiet cost of saying yes when they meant no. We compare our internal experience — which we know in full — to someone else's external appearance. It will never be a fair comparison.

So when we find ourselves exhausted, overwhelmed or stretched beyond our limits, it's not surprising that we assume we've failed somehow. The story we're often sold is that if we're struggling, we simply need to try harder, be more disciplined, or find the right solution.

But perhaps the more useful question is not "What's wrong with me?"

Perhaps it's "What am I responding to?"

What expectations have I absorbed? What pressures am I carrying? What messages have I internalised about productivity, success, worth and rest?

Awareness creates choice.

Not because awareness magically removes the pressures, but because it helps us see them for what they are. It allows us to recognise that some of the self-criticism we've been carrying may not have originated with us at all.

And in a culture that constantly asks us to override our own needs, there is something actually quietly radical about paying attention to how we actually are. About noticing when capacity is low. About listening to our limits instead of treating them as problems to solve.

So before you conclude that you're not capable, pause and consider whether capacity might be the real issue.

You may be more capable than you've been giving yourself credit for.

And you may be living in a world that makes it very difficult to recognise when your capacity has been exceeded.

It is perfectly ok to question the narratives we've inherited without needing to have all the answers.