Please choose the correct ending to complete the given sentence: Sports and Fitness: [header] How to stretch to improve your flexibility [title] Warm up your muscles. [step] Perform 40 jumping jacks , 25 squats, run on the spot for 5 minutes, and ten press-ups or ten girl press-ups if you are not strong enough. [title] Start with simple stretches to get used to the concept and feeling of stretching.

Ending1: [step] You can stretch on a ball or in the sky. Avoid attempting to do anything difficult or hard and figure out what you're doing properly. Ending2: [step] Does it feel to stretch? That is great. Start slow and do thirty chest presses before you reach bench pressing. Ending3: [step] Stretching is the single best way to exercise comfortably and to elevate your blood circulation. [title] Work your muscles with the backbend workouts. Ending4: [step] Stand up and stretch your legs into a wide straddle. Reach down until your palms rest on the ground, keeping your legs straight.

Answer format: ending1/ending2/ending3/ending4