Belly fat is not easy. There is no silver bullet that will make it go away immediately, minus liposuction ofcourse. That said, exercise and diet are the keys. Whether u prescribe to the cardio is the key (I dont) or resistance exercise is the way (it should be your primary source of exercise in my opinion), the fact you are doing something is the first step. Males store fat primarily in their stomach, but when it is burned, it is from all over the body. The best u can do is keep up the work, watch your diet and how things go. Just remember you have to push your body to respond. Your body can adapt to anything (picture Siberians chopping down trees with no shirt on in -20 degree weather). If u are only walking now for 90 min, try a fast walk for 60 and add 5 min of jump rope. When that gets easy switch to running for 30, 10 min of jump rope and 10 min of stair climbing. Diversity is the key. Maybe start a regimen of weight training. It all depends on what u have access to and what you are willing to do.