Hello, I am a master student in physics. I have come to realize that I will probably not work in a highly theoretical field in the future as I do not believe I stand a real chance in this world. However I want to learn as much as I can "on the side". Which set of courses would you recommend to get as far as possible in theoretical physics (QFT, QED, strings and their link to particle physics etc.) ? Including maths courses. Thanks!