Also if you do not qualify for military aviation due to age, vision, etc you might still want to consider the military reserves or guard in a non-flying capacity.

The pay gets pretty decent over time (for officers), it can provide the retirement that airlines won't (the medical may be the most valuable part of the package), and it will be good for your white-collar professional development and networking in case you ever need a fall-back career. If direct-action combat isn't your bag, there are many support jobs available...more of those than shooter jobs.

It is the easiest "side-job" to schedule around the airlines...you tell them when you will be gone, and the airline says "OK".

Obviously you need a desire to serve and a willingness to deploy in a combat zone.