1st step: Even though you do not have to have a bench to do this exercise, you will need to do this exercise with a couch or something else that is heavy and stable enough to place, brace, your feet, insteps, underneath it to keep your feet from coming up as you perform the sit-up, and this is especially true if you are using dumbbells that are close to or that are 25 pounds. If you do not have something to place your feet under to keep them from coming off of the ground, then you will need to do a Dumbbell Crunch instead of a sit-up. Once you are next to the object you are going to use to put your feet under to hold them down and brace yourself with, place the dumbbells near it approximately shoulder width apart.
2nd step: Next, face the couch or object and sit down with your feet and body facing it, between the dumbbells you set near it. Then slide yourself forward so that your feet can go under the couch or object so that your heels are still on the ground but your insteps, top of your feet are under the couch or object to hold your feet down. Your feet should be about shoulder width apart while your legs, at the knee joint, are bent at an angle that is approximately between 90 to 30 degrees. As long as the heels of your feet are touching the ground, and your insteps are pressing under the couch or object, you may proceed to with the exercise. After finding the angle that you feel most comfortable with, gently rest your back on the ground. Remember to keep your head off of the ground the entire time you perform this exercise, and not to violently bounce, jerk, or swing your body to perform the sit-ups with the weights.
3rd step: Now reach out your hands and grab the dumbbells and pull them next to your body near you side and hips. Then firmly grip the dumbbells, and in a very controlled fashion, smoothly, gently, and slowly pick them up off of the ground by using your elbows like a fulcrum of a lever, pivot point, and lift the dumbbell off of the ground and then lower the nearest end of each dumbbell that is nearest to your thumb on to or near your shoulders, near your upper chest, so that one end of each dumbbell is resting on or near your shoulder-upper chest with the other end pointing towards the ceiling or sky. This is the starting position. This is the beginning of the repetition.
4th step: In a very controlled fashion, smoothly, gently, and slowly sit up while keeping the weights touching or very near to your shoulders-upper chest while you breathe out. Keep contracting your abs until the dumbbells come close to or are in-line with your knees while maintaining a firm grip on the dumbbells. This is the positive movement of the repetition. This is the middle of the repetition.
5th step: In a very controlled fashion, while keeping the weights touching or very near to your shoulders-upper chest, smoothly, gently, and slowly lower yourself back down to the starting position as you breathe in, but do not let your head touch the floor or your back slam into the ground. This is the negative movement of the repetition. This is the end of the repetition.
Repeat steps 4 and 5 as many times as you need to do in order to achieve the set amount of repetitions for this exercise for the day.
6th step: Once you have completed the required repetitions, in a very controlled fashion while continuing to firmly hold the dumbbells, smoothly, gently, and slowly lower the weights back to the floor by using your elbow as a fulcrum. Now you can stand up and move to the next exercise.