Basically, at this point in my life I refuse to do any personal workout that takes longer than 20-30 minutes per day. I do not have the time, the energy, or the attention span to go much longer. Yet I still want a heart, muscle, and bone strengthening workout that will increase my heart's capacity to pump while also keeping me strong, toned, and flexible. I also have other dislikes (I am a picky fitness diva). Cardio equipment such as the treadmill makes me feel like a rodent on a wheel, yoga just annoys me, and weight equipment never seems to quite fit.
Luckily I discovered High Intensity Interval Training a couple of years ago. HIIT goes by a number of different names, such as the Tabata protocol, but the basic concept is that you only have to exercise for a few minutes if you work intensely at 90-95% of your maximum effort. To give you an idea of what that is compared to a standard workout, most treadmills suggest a fat burning zone that is about 70-75% of maximum.
Scientists at the K.G. Jebsen Centre of Exercise in Medicine in Sweden are currently conducting clinical trials of the HIIT approach. Their research to date shows that "for people who are in poor shape, just one 15 minute workout per week is enough to make a difference,"
as long as that that one workout involves 4 minutes of high intensity exercise.
So whether you love to run, bike, swing kettlebells, hang from your TRX®, or hop on that pilates reformer just make sure to get some short bursts of high intensity training in and enjoy the rest of your life.