Hunger issues

So i've been lingering a bit here seeing if i could find tips and one tip I found is to eat even though you're not hungry. While it sounded simple, I quickly realized it was easier said than done. It feels weird when i try to almost as if my stomach is trying to reject what i'm eating before i even eat it. I feel like if i don't get over this hurdle, I believe I will struggle a lot with gaining. I've tried heavy cream but it tastes awful and even when i mix it with something it just isnt appetizing at all. So with that i leave these questions:

How do you all eat even though you're sated?

How can you tell if you're "comfortably full"?

Im pretty much mentally prepared to do this physically however is where the problem lies.
3 weeks