Inc. Magazine writer Jeff Haden does a good job describing the rigors and benefits of interval training in this piece. The changes brought about at the genetic and cellular levels are impressive…literally life changing. Yes, it will be hard. And, yes, you will enjoy the benefits.

You can integrate interval work into almost any conditioning work, from fast walking to kettlebell and sandbag training to calisthenics to running, cycling, and swimming. So, unless you are doing pure strength work, you have few excuses to not do some intervals. Get after it.

The goal is to go well beyond what feels comfortable. Your muscles need to burn. Your lungs need to burn. If it’s not hard — really hard — then you’re not doing intervals.

And if that kind of effort doesn’t sound fun, think of it this way. In every other aspect of your life you try to optimize the outcome; you try to be as efficient and effective as you can with your time. Shouldn’t you take the same approach when you work out?

Inc.: The Best Way to Feel Younger: 1 Exercise That Will Change Your Body Most, According to Science.