Sometimes I meet mathematical problems I'm not able to solve, and after about 30 minutes of trying, digging, and looking for some number hints, I give up and lose all the desire I had, to solve it. Then, When I often sit with clear mind, at the end I become frustrated and lie on bed hours not doing anything. I assume, you all have different methods of solving unsolvable problems. How do you do it? and what do you do when you aren't able to find anything helping you?