I found that envisioning myself as a 'huge startup soon', or very successful in the near future is damaging. It's far more productive to focus on solving the most important problems, and not on the prize.
I tend to think a lot about a "huge startup soon" but not as a prize, but as a completely different set of challenges that needs to be kept in mind right now.
For instance, what I need to improve in order to become a CEO of a mid-sized company? What are my personality traits that limit company's growth?
Another example: the first employees you hire set the DNA of the company. If you hire them as an independent self-motivated agents, it is completely different story than passive helpers.
Also, it is important to reframe your venture into something bigger to avoid the trap of an eternal "side project", which you do not treat too seriously.
I actually see "Huge startup" as "3-6 months runway, 3 employees." I use that to justify short term sacrifices, but I find the work itself the best motivator.
If I'm having real trouble, I'll promise myself to do 30 minutes and stop if I'm not making headway. Most nights I continue after that for some time.