Take the early bus, the harder class, the cold start. Small chosen discomfort makes the unchosen kind less scary.

Discomfort you pick on purpose teaches your body that difficulty is survivable, in a setting where nothing much is at stake. The tolerance carries. When something hard arrives uninvited, your reaction is calibrated by how often you have been uncomfortable and fine, and that calibration gets built in small ordinary doses rather than dramatic ones.

Choose one thing this week that is slightly harder than necessary and do it without complaint. The colder shower, the earlier start, the version you cannot coast through. Keep it small enough to repeat.