One thing that helps is accepting that not everyone grows at the same pace, especially in terms of following/subscribers and that's just a fact. Once you can accept that part it'll boil down to finding healthier motivators for completing your work.
Personally I like to set short term and long term goals about publishing episodes or chapters. Like if there's a certain scene that I'm really looking forward to in my story my goal becomes reaching that part or if there's a character I'm eager to introduce they become the goal.
Goals related to art improvement have also helped. Lately I've been aiming to practice backgrounds a bit more often so I try to include them in at least one comic page or illustration that I'm working on. Testing out drawing perspectives, learning and understanding foreshortening and dynamic poses, and so on and so forth.
It's super easy to get caught up in the numbers and while every person is looking to gain subscribers sometimes you can let numbers be your only motivator, otherwise you'll feel defeated far more often because your expectations aren't always matching up with the reality and you feel demotivated. Hopefully the things I mentioned help, best of luck!