Friends.

This probably sounds selfish, but sometimes I forget the benefit of friends.  I'm an introvert by nature, which doesn't mean I'm shy or quiet, but actually means I draw all my energy from time spent by myself.  As I get caught up in my alone time, I sometimes forget all the wonderful things about spending time and investing in friends. Friends sit quietly next to me in coffee shops, while we both work and try to refrain from distracting each other.  Friends remind me of how amazing good friends can be and how much each and every person deserves the good company of a friends.  Friends remind me that I'm horrible at Apples to Apples.  They also remind me what it's like to be in a car (as opposed to a bus or a train).  Friends are just so invaluable.