Our DS7 is like this. We have cycled him through a bunch of sports, trying to find something he'd like. He has told us he "doesn't like any of the ball sports." We recently signed him up for fencing (his choice), and he loved it for about a month, then there was a week off, and when he went back, he seemed to not know exactly what to do sometimes, and so now he claims to hate it. I'm trying to set him up with some more one-on-one training, because he was having a blast until the one bad week. But he's not a natural athlete, so sports have been hard. Also painful to watch him sometimes, as both my DH and I are fairly athletic.
Would love it if he'd get into swimming, but he's been a polliwog for the last 4 years because he's so afraid. We did win a free month of tae kwon do, which we'll try as soon as we can fit it in. I'm thinking he'll probably like track, but he's still too young around here.
