Twenty years old is a little late, but after scientific and systematic training, you can still achieve something, mainly depending on the purpose of learning boxing. The best age of general boxers is between 18-26 years old, and the sports life of some athletes in good condition will be appropriately increased. Zou Shiming started to play professional boxing at the age of 3/kloc-0 this year. So it is no problem to start systematic study at the age of twenty. According to your height, it depends on your arm span. The pursuit of strength at the small level is not very high, mainly due to technical reasons. Find a famous teacher and train systematically. You should be able to participate in regionals or above in about two years. During this period, you can participate in some amateur competitions according to your own training quality, and then position yourself according to the actual situation.