what is the balance between work and play?

I know it sounds stupid but sometimes i wonder, is there even a difference? After all isn't work supposed to be fun? So if it is there shouldn't be a balance it should allways be fun. Or people just hate there jobs so theres no balance, personally I think its either one or the other so there isn't balance because its either fun which can be working and fun or theres just work which isn't fun.