Start with training 1 or 2 times a week. The body has to get used a new rhythm, specially if you did not train for many years. When you start by working out 4 times a week, your motivation might go down very fast. It is always good to keep balance with other areas in your life.
For top sports people, the line between being in perfect shape and actually getting sick can be very thin. This is because they push their bodies very hard.
-------------------------------------------------------------
Extract from a short interview with Haaije Pijl