In training, results are driven by pushing beyond your limits. While you should never overdo it, you need to go further than you've been to get as far as you can go. You're not going to get there by doing the same thing at the same level continually, you must push for progress.
Within a round, there can be many skirmishes of action. Train for the skirmishes.
Prepare your machine for many intense bursts and the endurance will follow
If you're looking for serious results, don't jog until you drop - sprint, stop and repeat. Jogging, like any kind of moderate exercise, will burn a moderate amount of calories, but will never produce serious results for fighting - because your body is unchallenged, the effects are diminished. Going at full speed in bursts, pushes the entire system and provides a workout that is something to grow on. This is true in all forms of exercise, not just running.
As a fighter, it is always preferable to keep your training functional. A workout for you is not about aesthetics, but rather a means to prepare the machine for fight performance. A bout is broken up by rounds and each round is comprised of varying moments of withdraw and attack. Therefore, a good approach for preparation is to match the training to the fighting - drill with varying intensity for several minutes then break, then drill again.
Endurance for a fighter is not about enduring 20 minutes of continuous action, no, rather it is about enduring episodes of action within periods of time. You might think of a fight contest as you would a war. You don’t engage in one long endless fight, you fight many individual battles. And even within a battle, or a round, there can be many skirmishes of action. Train for the skirmishes. Prepare your machine for many intense bursts and the endurance will follow.