Pen & Paper. For all the time that I spend daily in front of computers, when I must reason deeper and clearly about a problem, nothing beats sketching drawings

Pen & Paper. For all the time that I spend daily in front of computers, when I must reason deeper and clearly about a problem, nothing beats sketching drawings and doing some quick calculations by hand. Typing in a keyboard, physical or virtual, doesn't give me the same feeling of "flow" to my thought process. Also distraction-free.