Go for a walk and sit down at every bench you come across on your way, 10 times, and then get back up again immediately.
This exercise is actually a squat movement. Squats strengthen your hamstrings, hips, quadriceps and glutes. If they are strong, you are less likely to get injured. It also strengthens your core. A strong core improves your posture. You walk more upright and therefore more efficiently. Walking will be easier for you because of this.
Of course, you can also practise squats at home. It is important that you do it in the right way to avoid injuries.
How to do a squat:
Place your feet just a little wider than hip-width apart, toes pointing slightly outward. Arms bent and crossed in front of the chest, hands pressed against the chest for balance. Begin the movement by pushing your hips back and then bend your knees to sink as far down as possible, as if you were sitting on an invisible stool. Your back stays straight, your weight mostly pressing on your heels. Come back up to the starting position mainly by using your gluteal muscles. When performing squats, pay attention to the correct movement in order to prevent injuries to the back and knees.