39 is not too old if your rich. But then if your rich at 39, buy a helicopter and hire one of us morons to fly you around..............
Seriously, (for once) at that age you have to take a hard look at what is is you want out of flying. If its employment, you had better be prepared for about 3 years of starvation, before you can afford to eat at McDonalds.
If things like a family, home, car, food are not that important, I would say go for it...........
If its flying just for recreation, then you will have no problem at any age.