I can’t get rock hard anymore. Erectile dysfunction (ED), or difficulty achieving a strong erection, can be frustrating and concerning. However, it’s a relatively common problem, and there are several potential causes, both physical and psychological, that can affect your ability to get a “rock-hard” erection. The good news is that many of these causes can be addressed, and there are treatments and strategies to help restore sexual function. Low levels of testosterone (hypogonadism) can affect libido and erectile function. Hormonal changes can also occur due to age, stress, or certain medical conditions.