@Настя-Волкова That is such a good question! I don't have ADHD myself, but I've been through several art blocks over the years and periods where I definitely don't feel like drawing. It's work to me: work that I like sure, but work. When I draw I often get into a zen place where I just settle into a pace and it's sort of relaxing. But that's more often with personal projects, harder to achieve with professional work where you have directions and references and feedback. A lot of days I'd rather lay in bed watching Netflix with a hot cocoa than drag myself out of bed and draw all day. Some projects even feel like pulling hair. So how do I know I like drawing?
For me it's 2 things. First, I like creating something. By that I mean I like the final product. Sometimes a project has been hard to get out, but once I'm done and see the final result, I forget all the hard part. I feel happy and proud that I actually created this thing, this thing that didn't exist before and couldn't have existed without me. When I finish a project, I take a beat to just look at it. It's my reward! I like to save a few in progress shots and carousel through them, seeing how each step makes it better until the piece is finished. Sometimes, seeing the finished result is more fun than the process was.
Second, weirdly enough I never feel productive unless I've drawn something. I could have done all the errands and washed my apartment from top to bottom and I'll still feel like I didn't accomplish anything that day if I didn't create something. It may seem unimportant at first glance, but feeling productive is very important for happiness. People who don't accomplish things, like people who have been in an accident and are temporarily disabled for instance, often get depressed. When you feel like you're not doing anything, not contributing anything, what reason do you have for getting out of bed in the morning? What a depressing thing it is! And when I don't draw for a few days I definitely feel down. I feel the itch to be productive again. Unless it's a vacation of course!
To summarize I think the best way to describe it is that drawing is like a family member to me. I love it, but sometimes I don't like it. Sometimes it annoys me, some days I don't want to deal with it. But I still love it, it's still a part of me, and no matter how it can sometimes annoy me, if it suddenly went away I would grieve terribly.
I hope this helped at all! Everyone sees drawing differently so even if your experience is totally different, it doesn't mean you don't still like drawing. But maybe reading everyone's responses will give you some clues!