Sock tans

For the half marathon, in your current condition if you just get out and run that is the best way to train it. You have plenty of speed to run down your fuel supplies and destroy your quads and calves. So the more miles you put in (reasonably), the better result you will have as this will improve your fuel storage and muscular impact resilience.

For the depression, while you will likely never completely get rid of it, your ability to control it greatly depends on how well you do at being able to convince yourself to get out for a run daily. Think of your run as part of your medication routine. That is actually how I think of mine. I do not know what would happen to me if I did not run, and I do not want to find out - I never missed more than 3 consecutive days since I started. I do know, though, that at 40 miles a week I become more irritable. Before I started running at the age of 11 I had a hard time concentrating in school, and a modern doctor would probably have diagnosed me with ADHD or some other disorder. With that, I never needed the type of medication that you have to buy at a pharmacy - consistent running has taken care of it so far.