My two cents: karate and swimming.
Also, we told our son upfront he would need to stick out "the season" (we only signed him up for things that lasted about 3-4 months). After each practice or game I would ask, "What was challenging about today? " . I would end by asking, "What did you enjoy most?" Even if he said he "hated " the sport he could always find some aspect he enjoyed. When he was younger I may have had to help him find what it was he liked (could be the coach, something funny that happened , or something very simple). I believe we showed our son that we don't always like things,but that we stick to our "commitments" and we can walk away with something positive from our experiences.