Personally, I found that reading books or learning a new development stack makes me feel like I'm using my time wisely.
Contracted/consulting work pays the monthly bills. I am fortunate to currently have one main client that pays well and in a very timely/reliable manner. If careful on the spending side of the equation we can make it with me working about 12 to 16 hours a week.
Secondly, I have built a technology-platform to enable me to deliver premium structured services very efficiently. But now that I have done most of the technology build I am into trying to build the business connections. I have more trouble disciplining myself to do the sales and marketing tasks that this phase requires. And, even when I succeed at disciplining myself there is rarely the immediate feedback that you have been productive. With coding the feedback that says "productive" is almost immediate. At the end of the day I can point to a new feature that I created and tested and rest easy knowing that I have been productive.
With enterprise sales there are so many lags between what I do and the results. And, it is also a number game. Even if I am ultimately successful, I may well have faced 40 or 50 or even 100 rejections before the big break. While in the middle of a string of rejections, it feels more like "foolishness" than "productivity."
I like reading and learning like you mention. But those too can be distractions from what is really needed. Learning is fun and often productive but I find it can keep me from the business building activities that I know I need to engage in.
Back to Work!
"I may well have faced 40 or 50 or even 100 rejections before the big break. While in the middle of a string of rejections, it feels more like "foolishness" than "productivity."
I think to an extent, most entrepreneurs have to go through this. Don't get discouraged and keep at it :)