I'm 22 Years Old And Lift About 6 Days A

I'm 22 years old and lift about 6 days a week. I juggle lifting well with work since I'm in the military and have a lot of free time to conduct PT. But I've only been able to have sex at least once a day. And even for the first time it's hard for me to get hard. The "I'm just tired" excuse is starting to get a little old, any advice?