
Sitting in a full squat with your heels down and your weight back does not pressure the knees the way squatting with heels up does. Keep both heels down and keep your weight back on your heels.
People who are not accustomed to squatting often find that they are too tight in the Achilles tendon to sit all the way down. Many of these same people do Achilles tendon stretches every day, or at least they do a motion commonly taught as an Achilles stretch, but which barely stretches the Achilles. The "lunge and lean," is the least effective Achilles stretch. The post Better Achilles Tendon Stretch tells why and gives a better stretch to do instead. The squat is another good Achilles tendon stretch. It is a lifestyle stretch for the Achilles and lower back, and a hip, leg, and shin muscle strengthener. You get healthful natural exercise from regular daily life. Even if you can't get down to full sit, bend properly with both heels down for daily bending and you will get a free Achilles tendon stretch every time you bend, which is many many times a day. Holiday Leg and Abdominal Exercise tells more on this.
The trains here in Thailand have the luxury of a bathroom, including a squatting bowl. You can tell new tourists here. They are afraid of the bathroom. When we lived in Japan, even the gleaming modern Bullet train, the Shinkansen, had a spotlessly clean squat fixture. Train bathroomsgive you balance practice too, swaying with the train as it takes you to the next adventure.
Photo by Dr. Jolie Bookspan