He’s not too young. He can start to learn good training habits now. I think that weight training should not be the focus yet but we’ll get into that.
The gym can be useful if you make it a special environment for serious focus. You can start taking him to the gym to work on building lifelong habits, focus, and technique. This is also a great opportunity to get yourself healthy and be a solid role model for your son, and to build that all important bond with your kid.
Priorities at his age and experience:
- Develop positive health and fitness habits and lifestyle
- Learn to work smart
- Develop basic proficiency and physical literacy starting with bodyweight exercises
- Recline rows
- Planks and other midsection exercises
- Jump rope
- Callisthenics such as burpees, and jumping jacks
Make sure he becomes proficient at all of these exercises before he gets into more complex movements and begins to use weights. He will need constant supervision, and most gyms will require it.
Have him work on his running outside of the gym. For now, don’t worry so much about his speed and explosiveness. That will come as he develops his strength and efficiency.
Depending upon his maturity and commitment to good technique, at some point, using your judgement, you can start introducing him to light weights for high repetitions. Stick to simpler tools like medicine balls, dumbbells, kettlebells, and a stick or pvc pipe. Begin by having him apply these weights to the fundamental movements that he has already been practising. Let him develop further maturity, experience, technique and strength before introducing him to more complex movements.
Throughout this process the focus should remain on lifestyle, learning, and his relationship with you.
Keep the sessions short, varied, and fun. Take the opportunity to teach him about nutrition and sleep.
This simple approach can take you both a long way.