I agree with Fatty that you need the sincere desire to serve, and a hopefully an interest in all things military.

But it's OK to factor in some personal considerations too. Joining the reserves for short-term furlough protection is probably a bad idea.

But as a long-term plan, it is very compatible with an airline career. In some cases you can go full-time if you get furloughed, but you might also get to go full-time when you would rather not do so.

The retirement could come in very handy if your flying career to does not end with FDXUPS/SWA.

At least be open to doing the full twenty.

Also consider Navy and USCG...the navy hires some reserve officers off the street with certain specific educational credentials (Engineers, Intel, Public Affairs, Medical). The USCG hires anyone, with some preference for prior-service or degrees related to their environmental mission.