When is too much?

My DS 16 mths does alot of things but im just wondering when is too much? is it possible to burn them out?

Atm, DS is doing Playgroup on Monday (2 hours), Gymbaroo on Thursday (45mins) and swimming lessons on Fridays (30 mins) atm his loving all his activies, such a social, outgoing little boy, he learns so much from all his activies but i would love to get him into a soccer team but im worried it might be too much? I would do soccer with him on Saturdays runs for 45mins. Wat do u all think? too much? or fine as long as he enjoys these things?

He does spend the afternoons at home playing with the toys or we go for a walk to the park for a play.