Go running! Run is one of the oldest forms of cardio. It's proven, tested, and effective. The fluidity of running allows the body to move in its natural pattern. It also allow one the opportunity of one to connect with mind and body.
I used to think I could never run! I am over 40, have had 2 kids, have a really bad back, and horrible joints. My sister inspired me because she started running 5 years ago and looks amazing. I ran through the pain and started at my own pace. I am up to 12 miles a week and climbing. ANYONE can do it!! Just take your time an believe in yourself!