Doing art is about a permanent feeling of joy and suffering, maybe you don't like what you're doing right now because you're in a repetitive cycle, doing art not only means putting the pencil to work, you have to be very aware of details with your eye, if you don't like what you're seeing then analyze why and what could you try to improve,, look up for tools that will help you, look up at tutorials, other people's mistakes and how they overcame them, don't forget you're doing this for yourself or at least that's how it should be, and no matter what you do, you need to enjoy working on the progress of that future you who will feel more satisfied with their creations. If you doubt yourself, but you feel like you don't want to give up all your hard work, then you'll know it's time to push for more.