fishing in Singapore?

Ok I'm sure I'm not the only one on this forum with a problem like mine:
My son has been pestering me to take him out to do "cool" things like rock-climbing at some farm (I didn't know we had rocky farms in Sg...), but as an office guy who only gets his exercise from climbing the stairs to my mother's flat, I'm in no condition to do anything that extreme. Still, it's not often that the kid initiates the interaction right, and I figure I'd better spend time with him while he's still young enough to care (he's eleven) and things at work aren't too busy.
So, do any of you guys know of a nice, manly activity that won't be too strenuous? Maybe can try fishing...but don't know where to fish on this island.

Thanks in advance!