It's only ten kilometers, but I'm suffering. This shouldn't be this difficult; not so long ago, I could blitz that distance, and more, like it was nothing. I get through it by telling myself, as always, that "this will never be this hard again".
But it will. You are the moving average of what you do, not the sum of what you have done. A lot of the skills and capabilities I picked up in 2014 have rusted away from neglect during four years of building a startup.
When you build a company, you have to build it out of something, and you do: out of your life, your love, your will, ... your ability to run ten kilometers. I think an early version of Dungeons & Dragons modelled this well: magic is powerful but temporary. To make something lasting, via the Permanency spell, the magician sacrifices - no exceptions - one point of their maximum Constitution.
I'm thinking of capabilities, now, not as a steady incline but as an upward-trending sawtooth of slow rises and sharp drops. Losing them is not a tragedy but a tradeoff, a deliberate decision to invest. ("Investment" in a startup context often focuses on cash, but - particularly for bootstrapped companies - that's a minor component of the whole amount).
I signed up for this, and I'm aware that I'm privileged to have had the option. Getting hurt, and rebuilding quickly, is part of it: "Success boils down to serially avoiding catastrophic failure while routinely absorbing manageable damage".
I've taken manageable damage, and I will again.