Not being able to come to the barn and ride is a stressor for many people. I am often asked how they can keep their riding skills from becoming rusty. I often tell my clients that the best thing they can do is walk their dog in the woods, or borrow their friends dogs. The act of walking in the woods, the uneven ground, the rocky sections, ducking under branches, pulling invasive weeds, all engage our core musculature in dynamic motion.

Walking is not as stressful to joints as running, and it is easier to be conscious of your posture as you are moving along. If you have no access to woods, then the next best thing is to use curbs and slopes to challenge similar balancing structures.
Maintain your head over you trunk, not leading with your chin; keep your shoulders down and relaxed while maintaining tone around your torso from below your arms down to you hips. I wear a belt to allow me to feel what I am doing around my midsection. Lifting your knees and swinging your foot forward so your balance is on your back leg until your leading leg is reaching to the ground will help prevent stumbling and tripping.
Fresh air, and views outside of four walls, help to release pent up stresses. And when you can come to the barn, you will be able to enjoy your time there even more fully.