Train regularaly. Put it in your calander..."every wednesday afternoon and sunday morning I will be at the airport for four hours, rain or shine."
Nothing will wash away a newly-learned skill faster than two weeks of inactivity.
Become an airport bum. Hang out and talk to other pilots. Offer to help an old-timer pull his plane out of his hanger.
Anytime...ANYtime you're around pilots and airplanes, you're learning.
Make a lifestyle change and become an aviator, not just a guy with a pilot license.
You'll live longer and be a better person for the effort.