Leroy, you CAN share your medkits.
And achievements in my opinion are just pointless trophies for those vain enough to need to be able to say "I've got all the achievements".
I mean, wow, congrats mate, you spent five hundred ours playing some RPG to get the "Take 5,000,000 steps" achievement. Does you life feel any better? Or did your girlfriend dump you and your friends reject you?
/rant.