Riding a bicycle will hurt your butt. Swimming will burn your eyes (is chlorine still a thing?). Running might cause cramps.
When you start lifting weights - barbells and kettlebells - the iron bites you. Front squats chafe your neck. Back squats chafe your traps. Swings threaten to rip the skin on your palms. The bell bangs into you when you clean them.
You get better with your skill. And your body gets used to it. Your palms develop calluses, for example. Your hands get rougher and get used to picking up the iron. When the bell bangs into you, you take the bump rather well.
Calluses are a great metaphor.
When you start something new, it is difficult. It chafes. It hurts. It is mighty uncomfortable. But as long as you are persistent, you will get rather good at it. You will adapt to it. You improve. You level up.
You don't lift weights for a few months. And when you go back to it, your hands will feel tender after the first day. But in a few sessions, you will be fine.
Dealing with the discomfort of reading a book above my skill level is something I have more skill today than I did 10 years back. Rather than getting frustrated and throwing it away, I get frustrated and then calm down, and I go again. I do a bit more the next day. And soon, the book resembles English words.
You have successes in other domains - doing the same thing - developing your calluses. Fitness or fat loss is no different. You need to have the same patience and approach, after contextualisation, of course.