I know it's not ideal (we should always be studying our opponents at the tables when we're not in the hand)...
...but I fully admit that I usually play a puzzle game while I play poker, especially if I am single-tabling a tournament.
yes, tournament poker can be very boring if it is early in the tourney and you aren't getting any cards worth playing... so that's when I play Windows Minesweeper or Solitaire or Sudoku or do a crossword puzzle or play my personal hidden gem, Hexcells Infinite on Steam...
this helps me to pass the time while folding, and it keeps me from making stupid plays at the poker table because i was bored. LOL
For live poker, I always bring my mp3 player, music becomes my distraction.