I always took it for granted when I was younger because I was naturally in shape so I never took it seriously.

But then working on a computer and getting older made me gain a fair amount of weigt.

Fad diets and Fad exercise and Fad weight loss programs are all temporary and not that effective in the long term. Physiological health requires long-term maintenance not a temporary fix.

I think it's imported to get into a regular exercise habit as soon as possible and just make it a part of your daily life. You have time to figure this out in your 20s and it will pay off dramatically when you get older.

I highly recommend hiring a personal trainer for at least a few months to teach you proper form and theory and get you into a regular routine.