Recently read this interesting article on fitnees at lifehack.org: Sleep Your Way to Better Fitness - lifehack.org
This makes an interesting read for especially a person like me who is not into a fitness program, regular or irregular, but I do give a lot of stress on sleeping and eating right. Maybe that is the reason why I have been able to maintain my weight at nearly the same levels for the past 5 years. I think a weight of around 66-70 kgs is good for a body of 5' 5".
But that is not to say that exercise is not to be done. At times I do feel that some exercise is required for the body so that the muscles do not become hard.