Yes. I've had several things going on over the years, some on the back burner.

But the trick is finding something that doesn't consume your life (unless you REALLY enjoy doing it), and has benefits over just picking up premium trips (such as being home at night).

Mil reserves has historically been good... it pales in comparison to airline opportunities today but that wasn't always the case, and what goes around will likely come around. If you're just off AD, stay in the reserves even if it's a low-key non-flying admin gig.

Rental property can be a big PITA, I mostly outsource the management even if it means breaking even... intent is to own it all free and clear by age 65, don't really need income now.