The Brain Fitness Program, a 90-minute special about the benefits of mind exercise that aired last month on WGBH, has at least one local health buff determined to flex his brain along with his biceps. Personal trainer Gregg D'Andrea was so impressed by the show that he's begun incorporating mental workouts into the spin classes at his Needham gym, Gstarfit. For a lobe-up on Marathon Monday (4/21), D'Andrea recommends trying these brain stretches while you run:

1. Add the digits of each runner's number you see.

2. Scramble the letters on every street sign you pass to create running-related words.

3. Mentally reverse every chant you hear, then shout it back. (That'll get the crowd roaring!)