Dumbbells are bodybuilding exercises. If you want to be strong, I suggest you do push-ups. At first, you should do three groups 15 push-ups every day, five days a week, and rest on Wednesday and Sunday (note: it is difficult at first, so you need to persist, and the effect is completely different without one, and the movements should be standard). Add five push-ups every two weeks, and when thirty-five groups can do three groups, they can add one month. Remember to do a test in the first month and test a pull-up. You can usually pull six if you practice hard. Twenty will be enough after half a year (note: eight pull-ups do not use waist strength). After one year, the formation of biceps brachii and triceps brachii will be certain, and deltoid muscle will be divided into four or five pieces. And dealing with a person who develops well in the same year as you is just like playing, but it won't be too much problem for both of them to use their strength.