Most useful thing I have is my jump rope. It is great for a short intense workout and whenever it's raining or I am too lazy to go to the gym. I just jump rope for at least 15 minutes. It's definitely a great cardio activity and is great for building up stamina too and the best thing about it is it is enjoyable
You can't go wrong using free weights, that's what I use, the possibilities are endless what you can do with them. Anything that you can do with the stationary bike, treadmill, stationary weights, if you're a creative person can do the same thing with free weights.
I have my ad machine and I love it, it's actually fun to use and helps me get to where I need since I started using it I lost a few pounds.
