Keeping fit in Singapore

Singapore, with its lack of open spaces, generally well-developed personal services and a climate unconducive for physical activity, is not a place to keep fit automatically.
There are, of course, sports facilities available (and cheap), mainly at public housing (HDB) estates, and many private Condos have pools and sometimes tennis fields, but you really have to force yourself to actually use them regularly.
Asian food, with its focus on vegetables and seafood, is healthy in general, but of course one has to keep in mind that a balanced diet made from fresh components is best. Not every hawker stall and other culinary option in Singapore fulfills such criteria - and some should decidedly only be enjoyed sparingly.