I had cancer in 2014 and let's just say that lefty died and was removed. I was 34
My body decided to quit producing testosterone naturally around the time I turned 40. I now give myself shots every two weeks to get my numbers where they belong. I highly encourage you speak to your doctor and have your levels checked. It made a huge difference when my numbers got back in line to where they should be for a 40 yr old male, vs where I was.
Side effects, on injection days I get a knot at the injection site that stings for about 2-3 days. There are other options if you don't think you can poke your own legs. The gel you rub on your shoulders was not pleasant and a bad idea if there are any ladies in your household. (Last thing you want is to give your wife and daughters is testosterone unless you want to have bearded ladies in your home)