Why do people exercise? The most frequently answered reason is they want to look better. Looks are tangible, so they motivate us to spend the time needed to exercise. To be a disciplined thinker you need to see (noticeable) results to motivate you.
I recently had an idea that I sold for $50k. Yes, I sold an idea for a business. I think the business is worth every penny of the $50k but it originated from a single idea. I have a white board (very large) in my home gym that I write my ideas on. I work out alone so this one dedicated hour can prime my mind which by the end of the workout has produced one idea at minimum. Some are stinkers that quickly get erased, but others linger and support additional ideas and build on the original idea. I have had too many profitable ideas to ever quit this daily practice of thinking. Sometimes it is just an improvement on something I am already doing in my companies or a marketing strategy that i can implement in our next TV or radio ad. I can’t tell you how many profitable marketing hooks I have come up with doing a set of curls.
The point is that simply thinking is profitable. You need to set enough time aside to think every day. I encourage you to have something readily available to write on. Sometime it helps to write a word or two in a visible place to ignite the thinking process on a given topic. Thinking is like any other muscle; once you start exercising it, it will grow.