Im in my 20's as well. & I have found. Walking is great excercise. I do it on a regular basis. You just have to do enough of it to make it count. Like walk around your block, etc. You start
burning fat after 30 minutes. Remember that. It has toned my butt & leggs. It can also lift your butt! When I do it reguarly..My butt has lifted. I personally like to walk anywhere from 2-7 miles a day. At a good pace, none of that slow lazy walking. Can take anywhere from 35 minutes to 2 hours in my case. Depends on how much time I have on my hands & How active I am feeling at the moment..ha ha!