It's one thing to know building a company is hard, it's another to actually go through the process.
What's so hard about entrepreneurship is the lack of stability, and it's not trivial to understand if you never built a business before.
Building a tech startup is taking a ride on a roller coaster. You go up, then down, then up, constantly, for a long stretch of time, and you never know when your stomach is going to return your meal.
The entropy tires you to the bone. It starts with your mind: one day you go through a dopamine high, then you spend another one fire-fighting. The fatigue accumulates, until your body can't hold it anymore and you burn out.
Your startup status constantly goes on and off - at least from your position as a founder, metrics should tell otherwise - and you don't know what to say when a parent asks you about the wellbeing of your venture: it's a damn Schrödinger cat! What am I even supposed to say? I just say everything is fine and goes on with it. Talk is cheap, data doesn't lie and is devoid of ego.
This is why it's important to cultivate a stoïc mindset. Emotions, status, opinions, feedback, ego… as a founder, you must always nurture a stable frame of mind. Let it all flow through you, detach yourself from what limit your execution skills.
Most experienced entrepreneurs know it's important to have a routine. The market is always chaotic, all you can build upon is yourself.
Developping a thick skin, not giving a f*, having a high pain threshold… the metaphors are many. As a wannapreneur, just keep that in mind. Creating a venture is a long odyssey, and you need to develop mechanisms to stay the course.