Any new regime will entail some discomfort, but I was encouraged by the fact that the discomfort caused by this book's “Over 50 Program” coincided with the muscles that had objected so strenuously during my coughing fits. I continued this program until it became reasonably natural, and then progressed through the book's three General Conditioning programs. Most recently I have been alternating three sets of the third program with one set of either of the first two programs, with between one and two weight workouts per week. I fill in with stationary bicycle, elliptical trainer, or rowing machine for between three and five workouts per week.
I did note that my strength was sometimes inexplicably and wildly inconsistent. On one exercise, where you kneel and pull down to lift a weight, I found that sometimes 160 lbs was quite easy, while other times 100 lbs was extremely difficult. I could not correlate this variation in strength with anything in particular. At least not until I made a closer examination of the weight machines. It turned out that of the six stations, four provided a two-to-one mechanical advantage, so that when having randomly selected one of those four, I only needed to exert 80 lbs of force to lift the 160 lbs. Mystery solved! In another memorable instance, I was having great difficulty lifting the usual weight, then noticed that I had mistakenly attached to the barbell a pair of 35 lb weights instead of my customary pair of 25s. In another case where an unexpected doubling of strength surprised me, I learned that the weights were in pounds despite being in a country that has long used the metric system. Which is at least quite a bit less painful than making the opposite mistake! All in all, my advice to you is to check weight machines carefully and also to first use small weights so as to double-check the system of measurement.
I initially ignored the book's section on stretching, relying instead on almost five decades of my own experience with stretching. As you might guess, but this proved to be a mistake: Decades of experience stretching for running does not necessarily carry over to weight lifting. Therefore, as is embarassingly often the case, I advise you to do what I say rather than what I actually did. So do yourself a favor and do the book's recommended set of stretches.
One current challenge is calf cramps while sleeping. These are thankfully nowhere near as severe as those of my late teens, in which I would sometimes wake up flying through the air with one or the other of my legs stubbornly folded double at the knee. Back then, I learned to avoid these by getting sufficient sodium and potassium, by massaging my plantar fascia (for example, by rolling it back and forth over a golf ball), by (carefully!!!) massaging the space between my achilles tendon and tibia/fibula, and of course by stretching my calf.
Fortunately, my current bouts of calf cramps can be headed off simply by rotating my feet around my ankle, so that my big toe makes a circle in the air. This motion is of course not possible if the cramp has already taken hold, but rocking my foot side to side brought immediate relief on the last bout, which is much less painful than my traditional approach that involves copious quantities of brute force and awkwardness. Here is hoping that this technique continues to be effective!