I'm watching Life (2017) right now, and Jake Gyllenhaal just talked to Rebecca Ferguson about how he was a doctor in the military. Now I'm not an expert (on anything really) but that must mean he would have had to go to medical school, do his time in the military, and also spend all the time needed to become an astronaut.
Jake Gyllenhaal is 36. Can one do all those things in that time?
So basically what are some other examples of this kind of thing?