Frog bends are ideal if you don’t have much time or any other equipment. It relies on gravity and bodyweight resistance, and you can perform this exercise anywhere you can find a little floor space.
How to do it:
Lay flat on your back with your legs extended vertically. Turn your heels outwards and flex your feet.
Now slowly bend your knees outwards. Then straighten your legs out again to the starting position. You will feel your inner-thigh muscles doing most of the work, and 2-3 sets of 15 reps will be more than enough.