Every hit you take teaches your reaction time something. You flinch less the next time.

Exposure trains response. Each difficult thing you come through leaves your system slightly better calibrated: you recognize the shape of it sooner, you react with less alarm, you know from experience what recovery looks like. That is not the same as things hurting less. It means less of your time gets spent being surprised.

After something lands, take a moment to note what you now recognize that you did not before. Keep the specific detail rather than the general dread. Familiarity is most of what people mean by getting tougher.