If you don't have the metabolism for it, it's difficult to gain any serious muscle mass just by lifting. That was true for me anyway. I worked out off an on for years and made very little progress. Plus my recovery time was several days. The only time I made any progress was when I started taking supplements that had some structural similarities to steroids. Then my recovery time went down to around 24-36 hours and it was rare that I had more than a few workouts in a row where I didn't make at least some progress.
The problem though was that it really screwed up my moods. I already had some anger issues and this just made it worse. Also, lifting made me ravenous so I was gaining about as much in fat as I was in muscle. Once I got to the point where I could lift the entire stack on a few of the machines, I decided it was time to quit. It just wasn't worth it any more.