The first and most important thing you need to do is to learn to detach your sense of self-worth from drawing. Making a mistake or a bad drawing does not make you a bad person or a waste of space. It means you're still learning and that's okay, you shouldn't have any expectations of your skill level right now and you'll absolutely have days of inconsistency where you can draw a line perfectly fine one minute and then not at all the next - even great artists have days like that, it's just they're fewer and further in between.

I experienced this too going through the course, especially because I had previous experience, and felt that I should know this stuff already. One of the things that helped was speaking to a therapist and unpacking why I was placing these kinds of unrealistic expectations on myself, especially when no one else was holding me to that standard. So speaking to someone might be something that helps you as well.

I've quit drawing a number of times because of that annoying voice and every time I come back to drawing I've regretted it. I've had to make more effort to regain the attitude I used to have when drawing when I was younger where I would just draw whatever I felt like and wasn't too concerned with the result. I'm not sure why or how the mindset when drawing changed but it is definitely incredibly frustrating and hard to drown out the negativity. It's a common problem and you're definitely not alone in it.

The thing is if you do quit then you definitely won't get better. I try to take the pressure off of myself by treating this as if I was learning anything else; like learning a new language or learning an instrument. Actually I am doing both of these alongside learning to draw just for comparison. I noticed that I approached learning other topics totally differently than when I approached art; for whatever reason my expectations were much higher. For everything else I have no expectations and I'm much kinder to myself when I mess up in the other areas I am trying to learn. It made no sense that I got so angry and frustrated at not being able to draw how I wanted but did not feel the same way if I struggled to read a text in the language I was learning or made a mistake when playing the new instrument. Now I try to hold the same mindset when learning art and that frustration has lessened quite a bit.

Not sure if the above anecdote helps. It requires a bit of a shift in how you think about and approach your drawing and it's not easy. Be patient with yourself and try to find enjoyment in the learning and the process rather than your results.

I started learning a couple weeks ago myself and I've had the same experience. The best way to get over it is to understand that it's universal. Even most amazing artists look at many of their previous works and groan. Hell, I've been a game developer since I was about 16 and I still hate 90% of the stuff I've made in retrospect. It's about seeing your work not as an indication of your worth as an artist and more as a snapshot of your skills at that very moment in time. It'll get better as time goes on.

Also I understand this is not always easy. Worst case scenario if I can't make a certain stroke I want to make I'll just scribble like a mad man to get the frustration out and then Ctrl Z and go back to calmly working on a stroke I want to make.

Watch some Draftsmen podcasts.

I usually do it by reminding myself why I want to draw (that is, become better at drawing) - simply, to give life to the marvelous creations that live in my head. One day, my skills will be adequate for them to be presentable. So in the end, drawing is just a tool. A wonderous one, though.

This alone is the reason why I started to draw as a child. However, other circumstances led me to the neglect of this and now I am in the process of regaining the inner child and tackling the craft of markmaking fully.

You're not a useless waste of oxygen. Let up on yourself a little and try to enjoy what you are doing. I'm a complete beginner too and I understand the frustration of not being able to do what I want to with the pen (or pencil or any other medium for that matter). If you make a mistake that's all it is. Correct it if possible and move on. There's no need to dwell on it or take it too hard. We learn from mistakes (and we all make them) so if you aren't making mistakes you aren't learning anything. This course is hard. I can see even as a beginner that is has a lot of good advice and it is designed to improve your skill, so keep that in mind. I get frustrated with my lack of ability (meaning low skill) too, but hey, if I keep at it I will learn something and improve my skill level. Even though it is difficult, have some fun.