This book is primarily about using indoor rowing machines for daily exercise.  Your first task is to fit it into your schedule.  Find the time.  Decide on a place.  Get your own rowing machine if you want to do it at home. There are links to web sites of indoor rower manufacturers on the "Equipment" page under the heading "Begin."

You may not have as much time as you would like for exercise. But spending as little as five minutes on two additional activities at the end of your row will help you get more out of it.  One activity is stretching.  The other supplemental work most of us need to do along with stretching is strengthening our core.

The core area of the body is commonly thought of as the stomach area, including the muscles of the lower back, sides and abdomen. In most of us, the core muscles weaken from bad posture and lack of use. The core muscles need daily work, and need it increasingly as we age.

Expect to be very sore the first few days you do core exercises if you have not been keeping these muscles in shape. The soreness will pass and you will find yourself handling the core work much more easily after the first few days. To minimize that soreness, start slowly, easily, and with few repetitions.

I recommend you start your core work by selecting no more than one to three exercises to do each day. Repeat each a small number of times, up to ten, or hold the position initially for a short period, like ten seconds. You can increase repetitions or duration later.  If you are completely out of shape, consider starting with only one exercise.  Give the kneeling position below a try.

This photograph illustrates one type of sit-up.  Use a sit-up that works for you.  For the illustrated posture, sit up from lying flat on your back to the position where arms and legs are parallel to each other at forty-five degrees to the floor.  This is one of many types of sit-ups and crunches you can do for your abdominal muscles. If you find these difficult, begin with a simpler and more easily completed type of sit-up or crunch that works for you.

In this Superman position, you work the muscles of the back by holding up the arms and legs. Hold the position for a count of five or more, let down, and then repeat. This exercise can be deceptively simple. You should not strain to lift the legs high. Get the benefit simply by using your back muscles to hold the legs up slightly.

One variation on the prior position is to lift one arm and opposite leg to a higher position. Then switch which arm and leg you hold higher for dynamic back strengthening. Beginners may want to let the opposite arm and leg rest on or push against the floor when not raised instead of holding all four limbs up at all times.

Another way to do the opposite arm and leg core work is from a kneeling position. This position is especially useful in that you can hold the outstretched arm and leg parallel to the floor instead of trying to lift them higher than your body. This works the back muscles while allowing you to keep the back straight. Tighten the stomach muscles while you work the back.  I suggested this core exercise once to a neighbor who exercised diligently but suffered from chronic back pain.  The next time I saw him I asked him how it was going.  "That took care of it," he said.

Hold the body in a stiff position while resting on your toes and forearms on the floor.

Do the same on each side to work more core muscles.

You can repeat the same type exercise face up.

There are many other useful exercises for core fitness, including work on balancing balls and use of a roller. Find a small number that work for you so you will do them daily. Later, once core work is an established part of your daily routine, you can explore using additional ones and consider increasing how long you hold a position or how many repetitions you do.