Ballroom Dance Lessons for 3 years - Unfortunately, most men of my generation didn't take them, so I lost my knack.
Square Dancing - I've actually done this more (at least for longer periods of time in an evening) than Ballroom, so it wasn't a waste.
Guitar - I just didn't practice enough, so I didn't get very far.
Now, as an ADULT, I've taken lessons (paid for, and with a "pro") in a variety of areas with varying results.
Ski - terminal intermediate
Sailing- I can take over the helm, if I have to. I would hesitate to go out as the "lone" sailor
Tennis- I can't serve to save my life
Fencing- I haven't had an opportunity in decades, but I enjoyed it
Skeet- I'm a fair shot
Golf- I can think of better things to do with my time
Bridge- I'd rather play poker
Wind Surfing- I'd rather sail
Rowing- I can do it, but I'm not passionate about it (like DH)
Squash- Very few courts available; the one DH uses is not equipped for females (you have to go through the Men's locker room)
Horseback Riding- When my instructor (who owns the stables and had been riding since childhood, and teaching for about 15 years) was seriously injured by a horse, I decided to call it quits.
Driving Lessons- the best money I ever spent!