What should I do if I can't get an erection, can get an erection but it's not firm, or can get an erection but it doesn't last long?

Patient's question:

Impotence, weak erection, firm but not lasting, male, 22 years old

Doctor's answer:

Hello, practicing this method for a long time can warm the gate of life and ministerial fire, nourish essence and kidney, replenish the brain and marrow, making one energetic, light on the feet, agile in movement, and treating sexual dysfunction, impotence, premature ejaculation, lower back pain, frequent urination, insomnia, forgetfulness, nocturnal emissions, and involuntary ejaculation. If combined with Nei Yang Gong and standingGong, the effect is even better.
　　I. Rub the Yongquan: Sit in a cross-legged position, warm your hands by rubbing them together, then place your palms against your feet, from the heel along the ankle joint to the San Yin Jiao line, and rub back and forth 20-30 times. Then, rub the Yongquan point with each hand 81 times. Focus on the Yongquan, and maintain a slightly rhythmic hand movement.
　　II. Massage the Shen Shu: Place your palms on the Shen Shu points, with your middle fingers aligned with the Ming Men point. Simultaneously, massage in a circular motion from top to bottom and from outside to inside for 30 times, focusing on the Ming Men. Those with existing kidney deficiency and lower back pain can increase the massage frequency as appropriate.
　　III. Shake the scrotum: Lean your back firmly against a solid surface, adopting a half-supine position. Use one hand to support the penis, and the other hand to hold the lower part of the scrotum with your thumb, index, and middle fingers. Shake it up and down 100-200 times, then switch hands and shake again 100-200 times. Focus on the Dantian, gradually increasing the force. After mastering the basics, switch to using one hand to pat the scrotum up and down 100-200 times.
　　IV.：One hand is placed at the Hui Yin point, while the other hand is placed at the Qu Gu point with the pinky side facing forward. Both hands simultaneously rub the testicles and penis 100 times, then switch hands and rub again 100 times. Focus on the Dantian, gradually increasing the force.
　　V. Lift the Yang Gen: Place the labor point of one palm on the Dantian, while holding the penis with the other hand. Lift and pull it up, down, left, and right 100 times. Relax your focus, maintain a detached state, and keep a clear mind.