I have a bit of a theory around running
The first run is completely all about what you think you can do. It doesn’t matter how you fit you are – it’s more about how far you go till your brain says hey buddy it’s time to stop.
The second run (and this can be the very next day) you can magically run up to 1/3 even further.
It’s not that you got more fit overnight – it’s that you realise what you can do and are able to push through it.
Each run for the first week or so is just about stretching ‘what you can do’.
Then you hit your actual limit. You run at that limit for a few runs. Take a break. Come back and own it.
Apply this to most things. Your performance undoubtedly is what you think you can do rather than what you’re actually capable of.
Never, ever underestimate your potential.