I can relate to these feelings Lionel.
It's a good idea to have a little "talk to yourself" and discover what's going on... maybe you're really just tired and in need of a break, there's no shame in doing that, come back when you're ready if that's what you need!
Or maybe you're just bored with so many studies. One thing that really helped me out was starting to work on my own things from time to time. I know that this can be really intimidating, because we may feel that we are not ready, and that this is just a waste of time and the result will be trash anyways, but i think it's vital that we remember why we are doing this.
One rule that helped me out, as suggested by another student here on the forums was the 50/50 rule used in drawabox, here's a video where it's explained:
Or if you're just being distracted by other things, you may want to put some rules down for yourself.
I think that the most important thing is to have a honest talk to yourself and discover what's going on, and to not be too harsh on ourselves. We are only human, and we can only try our best!
Also, think in long terms! Your jouney it's not a race, it's a marathon, and there's no finishing line. Just keep it up at your own pace!
