The difference with your examples is that writing jokes every day is a fairly well defined, specific, verifiable, action. Getting good grades, "being" a start-up billionaire are not. I can't see you in the state of getting good grades, but I could see you study a little each day with the result that you get good grades.

I'm in grad school, so right now my goal is to read and understand at least one research paper every day. Once I get started, that usually balloons to several papers. The calendar method has proven very effective.

The point is that what should motivate you is your ultimate goal or dream, not a mental trick.

The problem here is that the mind works by mental tricks. Just because you don't think of them as tricks doesn't mean they aren't.

Don't you think it would be better to select the tricks that operate your brain by intention rather than by accident?

I don't necessarily agree to saying that the mind works by mental tricks, but that's mostly semantics. I do think it's generally better to operate by intention, and I also think that those intentions should be based on sound values and rigid beliefs and dreams.