Start with a duration you’re comfortable with and work your way up. I do some standing pushups and a couple of stretches at the end of my walk to round out the workout. No equipment necessary, just your favorite tree. Here is what I do:
Standing Pushups: Stand facing your tree and stretch arms in from of you, chest level and place hands on the tree a few inches apart. Keeping your body straight, slowly bend elbows until your chest is close to the tree and push back with a single thrust.
Work up to 20 reps. Works chest, and arms.
Place hands on the tree a few inches apart. Keep arms stretched as you bend back lifting your head chin up while contracting your abs. Hold for 10-20 seconds. Stretches back.
Front Thigh Stretch: Stand facing your tree and hold on with your left hand. Grab your right ankle and gently pull heel towards buttocks. Hold for 10-20 seconds. Then switch legs. Stretches the front thigh muscles.