A new book on willpower asserts that it's a muscle. That is, you can strengthen it with practice, and you can exhaust it with stress and overuse. This makes sense, and years of research back the idea.

Regular aerobic exercise and targeted resistance training exercises can help reduce abdominal fat, especially when paired ...

While the plank is an excellent core exercise, several other options can strengthen your core. You can do these bodyweight exercises anywhere, and they don’t require equipment.