Testosterone
"I am 53 years old, started having depression issues and my wife told me I had the same symptoms she had before she went on hormone therapy.  Had my testosterone checked and sure enough it was in the low range. I was about 280 which is the low end of normal but for someone my age too low. Doctor suggested injections to build it up in my system. First week I felt a difference within an hour after the shot. I felt like myself again and realized I hadn't felt this way IN YEARS. By the 4th day I started coming down, was told to get in the gym and work out which I suppose released more of the testosterone and felt better again. But by the 7th day started crashing. Just had my 2nd shot and feel great again."