As with many other activities that have potential benefits and harms, moderation is the key. Most of the harms that come from gaming can be improved, if not avoided altogether, by limiting the number of hours spent in front of the screen, and by engaging in healthy activities like exercising, or socializing in the real world instead of the virtual game world.
Education is an essential key to injury prevention. Gamers need to be educated on how to protect their thumbs, wrists, and elbows, their waistlines, their emotional state, their sleep, and their eyes. Simple education around taking breaks, stretching, eating healthy snacks, and resting and icing your thumb, wrist, or elbow when it starts hurting can address injuries early, before they become significant. For the eyes, gamers can try the 20-20-20 rule: every 20 minutes, try to look at something 20 feet away for 20 seconds.
In short, playing video games can be fun and a social activity when integrated into a healthy lifestyle that includes plenty of sleep, exercise, and good nutrition, rather than letting the game become your life.