Nobody gets issued the capacity in advance. It arrives during, which is why the first weeks of anything bad feel so much worse than the later ones — not because the situation improved, but because the specific muscles it demands hadn't been built yet.
Cold-water swimmers describe the same thing. The first minute in October is violent. By November the same temperature is merely cold, and nothing about the water has changed.
If today is unbearable, that may be information about how new this still is rather than about how it will always feel.