As a middle-aged individual who sits at a desk most of my days, I understand the necessity of exercising on a regular basis. But the older I get, the less inclined I am to kill myself doing HIIT (high-intensity interval training), spinning or anything else which involves copious amounts of effort and sweat.

And maybe it's because temperatures have been sub-zero where I live, but I have not been motivated to leave the house to go to the gym this winter.

It's fine. Here's why. A year and a half ago I discovered a different way of working out, which only takes 20 minutes a week and is remarkably effective. Essentially, it involves going to a special kind of studio wherein a trainer straps you into a machine and pushes you to work a muscle group slowly until failure. It was great. I lost weight thanks to building lean muscle mass which translated into a higher metabolism.

Then I quit. (It was expensive and an hour away from my home.)

But what I learned about high-intensity, slow-motion strength training stuck with me. In the last several months I have been effectively using a handful of bodyweight exercises to achieve muscle failure, without leaving my home office while saving a wealth of time getting to and from the gym.

This routine isn't for people with back or other problems.

Read and understand this: I have a healthy BMI, good cardiac ability and no back problems. What works for me may not work for you, and if you're in rough shape to start with, you could actually get hurt doing some of the exercises I recommend. If you're not confident you can handle this kind of thing, then certainly get the advice of a professional trainer or health care practitioner.

You'll need a distraction.

I recommend having some kind of distraction playing nearby, such as television or YouTube, since some of these movements take several minutes and the idea is to hold them as long as possible. (Boredom will make you quit them too soon.)

Minutes 1, 2 and 3

Get into an elbow plank position so most of your weight is resting on your toes and forearms. Hold one leg off the ground, so as to further engage your glutes, quadriceps and core. Switch legs every 30 seconds. During the third minute, switch every 15 seconds.

Minute 4

Sixty jumping jacks. This gets your heart pumping and works your arms and lower legs.

Minutes 5, 6, 7, 8 and 9

Lie on your back with your knees bent and lift your butt off the ground with your pelvis held as high as you can so the line from your knees to your shoulders is straight. Now just hold. Yes, it burns.

Minute 10

Sixty jumping jacks.

Minutes 11, 12 and 13

With your back against a wall, lower yourself so your upper legs are parallel with the floor and your knees are bent at a 90-degree angle. This wall sit is not fun--make yourself hold it the full three minutes.

Minute 14

Sixty jumping jacks.

Minutes 15 and 16

Get yourself into a reverse plank position, so your chest is pointed to the ceiling. Your legs can be straight, with heels on the floor, or bent with knees in a crab-like position. Arms should be slightly bent behind you (not locked, which is cheating). Hold through the burn in your triceps.

Minute 17

Sixty jumping jacks.  

Minutes 18 and 19

Reverse plank, again.

Minute 20

Sixty jumping jacks.

Do an alternate routine the next day.

Ideally, you'll do some form of bodyweight training every day. (Since it only takes 20 minutes, you have no excuse to skip.) On days two, four and six, do the following routine instead: 20 push-ups (on knees is fine), 50 squats (with weight, if you want) and one set of 60 jumping jacks. Repeat five times, for a total of 100 push-ups, 250 squats and 300 jumping jacks--all in 20 minutes or less.