I don't have a ton of respect for the authors of this newsletter, but this truth is particularly well expressed:
"Regular physical activity promotes general good health, reduces the risk of developing many diseases, and helps you live a longer and healthier life. For many of us, “exercise” means walking, jogging, treadmill work, or other activities that get the heart pumping.
"But often overlooked is the value of strength-building exercises. Once you reach your 50s and beyond, strength (or resistance) training is critical to preserving the ability to perform the most ordinary activities of daily living — and to maintain an active and independent lifestyle.
"The average 30-year-old will lose about a quarter of his or her muscle strength by age 70 and half of it by age 90. “Just doing aerobic exercise is not adequate,” says Dr. Robert Schreiber, physician-in-chief at Hebrew SeniorLife and an instructor in medicine at Harvard Medical School. “Unless you are doing strength training, you will become weaker and less functional.”"
Living is moving. If you can't move, your life is diminished. This is the potent, valid truth behind fitness - you don't need exercise to burn calories and lose fat (if you eat the right food, your body will regulate intake far better than you can), you NEED EXERCISE SO YOU CAN HAVE A GOOD LIFE! So you can have choices, so you can keep living almost as long as you are alive, so that you can love full speed, play full speed and have the impact on those around you that will make your death a cause for grief.
Don't aim for hours on the treadmill, aim for more strength, more mobility, more power (for example jumping, sprinting and other speed work), more tests of balance, more coordination, higher skill levels, and always working for variance. Invest in quality of workout not quantity.
BUT, don't give up the good because you can't be perfect - at least do something! Do whatever exercise or movement you like and will do, and work for something better over time.