The swim teacher who held you up the first time you floated was trusting your body before you did.

Somebody had a hand under your back and was betting on a body that had never floated before. That bet is usually how ability begins: a person acts as if you can already do the thing, and their steadiness buys you the few seconds you need to find out. You were not trusting yourself yet. Someone else covered that part for a while.

Look for who is doing that for you now, and notice it instead of letting it pass as normal. Then take a turn. Hold the kickboard for a kid, pass to the player who never gets passed to, tell a beginner they are closer than they think.