Unfortunately, we can't spot reduce fat, and for most men, we store fat in our belly. To reduce belly fat, we really need to reduce weight (hopefully mostly fat). There has to be a calorie deficit, so either increase your calorie burn through activities or reduce calorie intake; for best results, do both. Sadly, belly fat is the last to go, but don't be discouraged, you will see major improvements in overall health and aesthetics along the way.