If you’re a nurse then it’s officer time for you! I’m in the process of rejoining the reserves in a non medical role as I fancy something completely different! As a reserve you volunteer to deploy rather than get sent and from joining to ready to deploy takes a few years normally anyway.
My wife isn’t keen, but understands my need to “play out” I plan to up my commitment and then look for a safe deployment where family can come too (Cyprus/canada/ uk training roles etc).
As for running, I’m a fatty, map a mile and a half and run/ walk as fast as possible at least thrice a week, working up distance rather than time, as a cyclist I found it was legs not lungs that let me down but I’ve dropped from 17 mins to 13 in just a few weeks of training, though I am struggling with the upper body strength a bit!