Whenever I sit down and just think about stuff I feel irrationally guilty that I'm not actively working. THIS IS BAD!!!
It's very important to remember that in creative work of any kind (this includes things like programming tbh), the more time you spend getting your thoughts in order, the smoother your execution will be. Even just taking a walk and letting your brain air out a little can be invaluable. 100% efficiency does not mean 100% active work.