Thanks for sharing your experience and situation. I always appreciate entrepreneurs who tell it as it is rather than constantly glamorizing the dreams. As a fellow entrepreneur who does everything, it is definitely exhausting to handle. Every problem, issue, and solution is under our control. That extra hour of work can be fully utilized to move things forward. There must not be any harm in working a few extra hours then? Right? Wrong!
If you're in this for the long term, you need to make this journey sustainable.
1) Understand and internalize the power of breaks: You need them every hour (e.g a walk), every day (e.g. meditate/exercise), and every few months (e.g. vacation). Although you may think you can work at 100% efficiency all the time, it degrades very quickly. Breaks are conscious activities that give your mind a break from everything.
2) Form a support network: Find peers and mentors that you can engage with on a regular basis. Share experiences and realize that you're not in this alone. Everyone is in a similar position and each has something to contribute.
3) Get inspired: You ask this in your original question but wanted to address points #1 and #2 regardless. It's important to rekindle your passion very often. Talk to your partners and customers in an intimate setting over coffee or dinner. Understand how you are addressing their needs and what your service is now enabling them to do that they couldn't prior.
I would be happy to share more insights and examples of each of the above points. Just remember, you are not alone and you can do it! Best of luck and feel free to reach out.