Matt, it’s great to hear that you are enjoying o-chem. I also thought it was just the coolest thing - probably my favorite of the prereq classes. It’s not everyone’s cup of tea obviously; you’ll hear more complaining about o-chem than any other prereq I think. And Denise is right, the labs are awesome. I loved all that neat glassware. 
Internship is hard on your health, no two ways about it. I was just talking about this today with a fellow intern and both of us were bemoaning our declining physical states. Some really dedicated people probably find time to carve out for the gym but I am not dedicated enough. If I’ve been at the hospital since 6am, when I leave at 6pm I am NOT thinking about stopping at the gym on the way home.
And then there’s the food. The first two rotations I’ve been on featured breakfast EVERY morning - bagels, doughnuts, muffins. Sometimes (not always) fruit. Coffee. I don’t want to THINK about my blood pressure after the increase in caffeine consumption. On some services, there’s lunch (almost) every day as a way of enticing the house staff to come to the lectures: pizza, wraps, deli sandwiches, or full-fledged hot meals. Urp. It takes stronger willpower than mine to resist all this food. It’s especially tough when eating is tied in with emotions, as in, “I had a $hitty night on call, I deserve this jelly doughnut.” 
Finally, don’t take for granted those relationships with adults. Stressful things can and do occur - life, unfortunately, is unpredictable. Make it a priority to maintain good frequent communication with the folks you really care about. The people who love you want to know what’s going on in your life and how much you are enjoying it. Many of us have made the mistake of sharing only the angst and the pain of pre-med and medicine. Our S.O.'s and other loved ones understandably start to wonder, “Why is she doing it then? What is the point if she is so miserable? And why is she choosing misery over spending time with me?” Keeping lines of communication open doesn’t need to be any more complicated or time-consuming than, “Tell me about your day, and then let me tell you about mine.”
Mary