I think it's a shame when a young child can reel off a list of things they've tried and "dropped". My Dniece is 7, and has already tried and rejected swimming lessons, ballet, Irish dancing and gymnastics. She didn't do any of the activities for longer than about 4 or 5 months, excpet swimming, which she kept up for longer. Her sister (5 yo) has rejected football, tennis, swimming and ballet. When my Dsis and I were growing up, we both learned the piano. She stuck with it from age 8 to age 16, and got pretty good, but never loved it. I was 6 when we started, carried on with lessons til I was 18 and left home, and still play for pleasure now. In her late teens, Dsis decided that our parents "made" her learn it, and vowed that she would never "make" her own children do things. My own DTDs (4.8) have been doing ballet and gymnastics for over a year, and really enjoy it. If they fuss about not wanting to go (rare) then I take them anyway, and by the time we've arrived and they've seen their friends, their enthusiasm has generally returned.
I think as a parent, it's really really important to teach children from an early age that committment and perseverence are often just as, if not more important that inate "talent". I now teach Performing Arts at Secondary School, and am currently tearing my hair out daily at kids who have parts in the school musical, are really talented but don't show enough committment to turn up to rehearsals.
Whilst extra-curricular activities need to be fun and enjoyable, I think it's really sad when children are just told "OK then, you don't have to go if you don't want to" by parents.
PS Dsis now says she wishes she'd kept the piano up. I wonder if my Dneieces will wish the same when they're older.