Intensity is not about what you do. In fact, what you are doing is completely irrelevant. Intensity is about how you do whatever you are doing. It is about your focus and your effort. Intensity can be taught on the mats but it has to be developed off the mats so that it permeates itself into all aspects of your life. If you want to earn a black belt, intensity has to be present in everything you do, not just your training.
If you are withdrawing and not engaging, you are extinguishing intensity. It is difficult to stimulate intensity if you never venture outside of your comfort zone. Staying in the present moment and proceeding boldly is the kindling that fuels intensity. Always be aware of where you are and what you are doing.
“The best training program in the world is absolutely worthless without the will to execute it properly, consistently, and with intensity.” - John Romaniello (b. 1982)