I meet many Karate instructors and students. If a student were to ask me what he could do to become better at Karate, for many students I would reply:
I don't think that you can be good at Karate if you are out of shape. Hypothetically, if you (out of shape) were to compete against an equally skilled twin (in shape), you would almost certainly lose.
Skill is part of it. The other part is conditioning. You need both, in balance.
The best Karate instructors I know are in excellent shape. This is not an accident. They work at it.
Even if you do not practice Karate, getting in shape is extremely important. It will make you healthier and more able to resist sickness and disease. It will also give you more energy to work and enjoy life.
Charles C. Goodin