Play Chess

Powerlifting or Bodybuilding.

Build models or Model Railroading.

Read and Write and little else.

Get a Masters degree, then a PhD:

History or Military History

Psychology (the mercenary in me says to do this one)

MFA in Creative Writing

Political Science

Buy a Classic Ford Mustang and fix it up (or a Porsche, a Mercedes-Benz, or a Land Rover)

Buy a Harley-Davidson.