In Victorian times, prosperous men flaunted their pot bellies as an enviable sign of wealth. That's not the case today, when such girth is known to be a serious marker for heart disease, cancer and many other undesirable outcomes.
Exercise can tone and define your abdominal muscles, but if you're carrying more than a few pounds of excess weight, the best (if not only) way to flatten your stomach is add a calorie-controlled diet to your workout plan.
Start with Table Push-ups
There are two components to a flat belly: a well-developed wall of abdominal muscles and a minimum of abdominal fat. The former is achieved through exercise, and the latter is mostly achieved through diet. As an old saying goes, the best exercise is pushing yourself away from the table. In other words, start counting your calories.
That's especially true if you have more than a few pounds to lose, because even the most rippin' six-pack abs aren't even visible if they're buried under 20 pounds of fat. A balanced diet that's abundant in fruits and vegetables and whole grains will leave you feeling satiated while creating the calorie deficit you need to trim your tummy.
Crunch or Sit-up?
Back in mid-century America, you did old-style sit-ups, which were once regarded as the gold standard of iron-gut, military discipline. Maybe they still are, so if your idea of "manly" is messing up your lower back, go for it. But few fitness trainers recommend old-style sit-ups, though there are some re-conceptualized versions of them that might work for you.
Crunches work the mid- to upper-rectus abdominis, while diagonal crunches will sculpt your external obliques, the muscles that run down either side of your abdomen. There are numerous types of crunches; learning these variations will put you on the road to a flat belly in no time.
Leg lifts tighten the lower rectus abdominus, and they strengthen the inner and outer hip muscles. As with crunches, you can adapt them to emphasize your own particular areas of underdeveloped muscle with numerous variations. This is to say nothing of the wonders they will do for your lower back muscles.
As a hard core challenge, leg lifts may not look like they'll put heavy lifting competitions out of business, but they're actually quite strenuous. Start with basic leg lifts and then branch out from there with other versions such as scissor kicks.
The plank is a yoga position that is basically a push up at the top of the action; you're suspending your body in a straight line from your toes while holding your body at an incline with your arms pressing straight up from the ground. Better yet, you're squeezing your abdominal muscles while you're holding the position. This works the transverse abdominis, the deepest-lying of the abdominal muscles. Though not visible, strengthening it will enhance your core stability and posture, both of which add to the effect of an upright profile.