Help me gain weight and also be fit

[That Foreign Guy]

Assuming you don't live in a submarine, you don't have to do cardio at the gym. Go for a run, play basketball, run up and down the stairs of your building, jump / step on and off a chair, etc.

I used to do Tabata rows / elliptical after lifting and it wound finish me off nicely. However, as the intensity of my workouts have gone up (especially after changing to supersets in places) I find that I just can't face it at the moment so I'm sticking to playing squash on my non lifting days (another non-gym cardio idea).