KIAWAH ISLAND, South Carolina: Phil Mickelson is not the first middle-aged person to change his diet and engage in brain training in a quest to feel and perform better, but he is the first to win a major golf championship after turning 50. While Mickelson's performance at the PGA Championship might not open the floodgates to a sudden glut of Senior Tour-eligible winners, it at least will provide further evidence to those creeping up in age that it is not too late to