This is the panic of the male beginner. In a non-sexual social setting, physiology usually cooperates. Anxiety kills arousal. If it happens (rarely), you simply roll over, sit down, or get into the pool. It is a non-event. Most clubs have a "cover-up if excited" rule, but experienced naturists know this is a non-issue.
Over time, exposure therapy works. You see a 70-year-old woman swimming confidently. You see a man with a colostomy bag playing cards. You see a teenager who is all elbows and knees laughing without hunching.
In the clothed world, a bank CEO looks different from a janitor. A fitness influencer looks different from a computer programmer. Clothes create a visual caste system of desirability and wealth.