Are there habits to keep a man's reproductive system healthy?

Yes: Keep clean and hygenic in the area of the genitals. Practice safe sex. Exercise and eat a healthy diet. Have a good emotional life. Avoid tattooing and piercings. Love the one youre with and vice versa and do everthing to moderation.

Have more sex: The “use it or lose it” dictum holds true, especially for sex.

Diet and exercise: Sexual and reproductive health is tied to your general health. Eat fresh fruits and vegetables, exercise at least 150 minutes/wk, drink enough water so that your urine is mostly colorless, have safe sex, maintain healthy weight. Get vaccinations recommended by your doctor.