If you start showing any signs of an enlarged prostate like troubles with ED, frequent urination, needing to wake up multiple times a night to urinate, then you should be having your doctor take a look at your prostate regardless of age. I feel like the average age for a prostate exam is too late as they usually happen around 40-45. I think that doing an exam even as early as 35 makes sense because of how important this all is to your health! If you're interested about the ways you can massage y