Your first lap of the pool might leave you hanging on the wall gasping. Lap ten won’t.

Fitness arrives faster than almost anything else you can train, and the early stage is brutal mainly because you have nothing to compare it with. Hanging off the wall after one length is not information about your capacity; it is information about this week. Four weeks in, the same length is a warm-up.

Count sessions rather than how each one felt. Go three times a week for a month and do not judge any single swim. Write down how far you got the first time, since in four weeks you will not believe it.