Tips link: Fastest way to lose 20 pounds, according to Women's Health. Including this body weight workout times a week, doing 2 sets of each exercise with reps per set (Note: 30 sec. plank) to help prevent injuries.
The first one works if you just straighten your bottom leg and kick. The second one is great, but it hurts your pelvis bone, so get a yoga mat and support your pelvis instead of having your hands in front of you. The last two are great as is. All give a g