Do what I did with my son... take him to the pool everyday and let him do what HE wants to do. If he wants to sit on the side with his toes in, that's cool. If he wants to play Matchbox cars in the shade, that's cool as well. Every now and then, ask him if he wants to get in and BE THERE to help him if he does. Have floaties for him, and/or a ring for him to play on. Take him to Walmart and let him pick out his own pool toy. If he still doesn't want to get in, play with the toy yourself and have fun doing it. If he sees you're having fun (and not scared), he'll be far more likely to want to join you.
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