ual Problems with My husband? He's embared.?

He's getting ready to turn 25. We have been married for going on 2 years. We used to have multiple times a day and everything was great. I even got pregnant once, but miscarried. The past year, however, we hardly have had at all. This is because when we do he cannot seem to . He is a bit tiresome all throughout the day and often complains that he is too tired to have . He is a bit overweight, but not by much. His physical activity, however, peaks at walking around a huge store for 8 hours a day and lifting/storing heavy boxes. He's never had any problem before, but now it seems that he can't. He can go on for long periods of time and never . He says he always feels like he is going to and continues to do as he sees fit, but never actually s. What could be the problem? He won't take my advice and go to the doctor and is too embarred to talk to anyone himself.