Specialist - Accumulate 10000 heal points health in a single life.
Thanks to the on-hud Chief of Staff achievement tracker, I can see that on a good life I'll accumulate ~1.8k-2k healing. My record somehow is 6.7k, but I can't even remember what I did so special on that map (all I know it was CP Egypt; perhaps that server rigged medics in some way).
How would one heal 10k hitpoints in a single life? Overheal many different team members? Uber like there was no tomorrow?
Achievement servers and maps need not apply. I'd rather not earn an achievement than just getting one.