I have a saying that has been my mantra so to speak for probably the last 25 years - It's Only Yarn!
When I first started knitting in 1990, that was NOT my philosophy. In fact, I was a bit intimidated when it came to my knitted projects. I felt that I had to get them right, the first time and if I made a mistake, I somehow failed.
I learned that making mistakes is part of the learning process and if there is a pattern error that I didn't catch quickly and is not going to change the outcome of the project, I leave it. Those are called Design Elements!
Also I love the process of knitting. The movement of my hands creating stitches and moving them from one needle to the other. It is very relaxing to me. So frogging a section or a complete project is alright.
Also the magic of knitting is that you can use that yarn to make something else! That is a game changer when you can adopt the mindset of the concept. You didn't fail if a project didn't turn out like you thought it would, it was just not the right pattern or yarn or time for that project.
I think working with glass has helped me with the ability to let go of a project. Many times I could work on a glass pieces and all of a sudden, it shatters or a piece breaks off. There is nothing you can do to save that broken piece. You have to start over. Also, you can't use any of those broken pieces so maybe that is why I love the fact that yarn can be used again and again.