Per Wikipedia:
Car accident [edit]
On January 11, 1977, one day before he was set to shoot one of the needed scenes in Star Wars, Hamill was in a car accident in which he fractured his nose and left cheekbone,[6] which required seven hours of surgery. As a result, a double was used for the landspeeder pickup shots.[7]
It does not seem that this particular accident hurt his career. No other accident was noted.
He was still recognizable in "Criminal Minds", though he has gained weight and looks aged. There are many 50 and 60+ year olds that do not look their age (celebrity or not) and are in great shape. Mark is just not one of them. However, as Auspoz points out, some us do not get to reach that age regardless how the aging process goes or a great physique.
Nonetheless, it was good to see him acting and breaking from the "Goody-Two-Shoes-Hero" typecast.