I know it may sound like a waste of good money after previous bad purchases, but have you considered investing in a rowing machine? Not like the one you purchased from a mail-order catalog, a pneumatic piston contraption that felt nothing like real rowing. The one that broke within a week, just like the home gym sitting in your garage. I mean high quality equipment. It's like your mountain bike, but you can use it for just a few minutes while watching TV, instead of getting sunburned outside.
If you can find a good rowing machine, it will feel like you are actually on the water. Another nice thing about these machines is that they are very quiet. You can still watch TV while you exercise. These machines are no impact, and they are easy on your joints.
The best thing about rowing is the full-body workout that it gives you. It works your legs, arms, and even your back. For a complete workout, just add in few pushups for your chest and triceps, and you've got a fully balanced workout.
Not only is rowing a full body workout, but a rower can be used to train a variety of energy systems. Need to improve your pure strength? Crank the resistance up to the max and do short sprints. Want more endurance? Turn down the resistance and shoot for time or distance. Feeling competitive? There are rowing machine competitions, which will give you a goal to shoot for while training and help keep you motivated.
Invest well and beware of diminishing returns. A new company out to sell a $1000 rower may or may not be a great deal, however, a reliable and established company is likely to have a stock of replacement parts. When in doubt, it is best to buy used. People who love rowing seldom give up their rowing machines. But at times this machine breaks down and the owner is not aware that it can be still be easily fixed.