Since I'm still deciding between a PhD in Clinical Psych or going to Med School, if I couldn't do the latter, I'd probably do the former (though getting into a PhD program in Clinical Psych is not a laughing matter...of course the PsyD is also an option).
If not that, then maybe PA school. Could still practice medicine and make a good salary so the trade-off wouldn't be horrible in the least.
If not that...well maybe physical therapy since I enjoy weight lifting and the physiology behind it.
...and if not that...well I'd probably try my hand at becoming a police officer. Because why not?