Various modes of exercise can confer health benefits and help the body burn deposited fat in the abdominal area. Specifically, aerobic training is effective at using stored fat for fuel and burns the most calories while you do it, so it is commonly recommended for weight loss. However, the challenge that many people run into when performing cardio exercise is that they tend to not push themselves and thus work at too light of an intensity to burn a significant amount of calories.
The good news is that even a program of low-intensity walking can reduce dangerous visceral abdominal fat stored deep in the body around the organs, which improves cardiovascular health and aids in weight loss. However, you asked about hardcore workouts and belly fat, so I’m assuming you are referring to the stubborn subcutaneous fat that is stored over the abdominal muscles and hides from view the coveted “washboard abs.” In this case, a walking program will be too light of an exercise stimulus to get rid of the fat over the abdominals.
My recommendation is to consider trying any type of high-intensity interval training (HIIT) program. These high-intensity programs challenge the anaerobic threshold (the point during a hard workout at which you feel that it’s difficult to breathe) and rev up your metabolic engine so that your body burns a higher rate of calories post-workout. Check out the resource link below to view recommendations and examples for this type of training.
In brief, high-intensity intervals are done at an exertion level of 7 or higher (on a scale of 1–10), and are typically sustained for 30 seconds to 3 minutes, although they can be as short as 8–10 seconds or as long as 5 minutes; the higher the intensity, the shorter the speed interval. Recovery intervals are equal to or longer than the speed intervals. If you are not used to this type of training, be sure to ease into it and progress slowly with the length of the high-intensity intervals (e.g., start with a work interval of 10 to 20 seconds, and then rest for 40 to 60 seconds before hitting it again). These types of workouts are intense, but they are over quickly, so many people find them a welcome break from the longer 30- to 60-minute workouts typical of low-intensity programs.