Hi I am a 21yr old weighing 125lbs. and 5'6, I have never been to the gym before and I want to know whats the best thing I should take in order to gain massive mass in the shortest amount of time? My little brother who is only 17yrs old brother has way more mass than already and its pissing me off. I have a very low sex drive and low energy so I thought I had low testosterone so I went to my doctor to take a testosterone level test and he said everything was all normal. All help appreciated, thanks!