Which is better, bodybuilding or running for a healthy young man?

What are your goals? Running has the effect of increasing metabolism and circulation leading to healthy cardiovascular (heart) function and lean muscle mass. Some form of cardio is important to any long-term workout plan. Long distance runners generally strive for a lean physique that is more efficient to the sport. If you want to develop and maintain muscle mass, resistance training is best.

Exercise, any exercise is good. For healthy diet: http://www.choosemyplate.gov/., exercise 30 minutes/day, drink enough water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs. Get HPV vaccine. Wish you good health! Safe sex: https://www.hopkinsmedicine.org/health/wellness-and-prevention/safer-sex-guidelines