Replying to Advice on small work out routines.

so i'm sure there's a few of you on here that are like myself. I'm tall, athletic build, never really had a problem with weight or what not even tho you never work out..

buut, as i'm getting older, and as i went home for the holidays and my brother saw me without a shirt and said, "deng, you've put on some weight." i've realized i should probably start doing a small work out of some sort.

so i'm asking you guys. what small work outs do you do to just keep you fit, keep the chubbiness off, and just stay a bit healthier? i dont want to bulk up or anything, just to stay lean.