Ultimately I find the best way to maintain a sense of reality and manage your expectations going into a deep run is to think about how realistic the possibility of you winning the tournament actually is.

For example, say you're going into a 9-handed final table. If the winner were drawn at random, each player would have roughly an 11% chance of winning the tournament. If all skill levels were equal and the tournament played out as normal, the biggest stack would have the best chance of winning the tournament, followed by the shortest stack – so while an average stack may still have an 11% chance of winning, a short-stack may only have a 5% chance, while a monster chip leader may have a 20% chance. If all skill weren't equal, and the big stack were the best player at the table, he might be able to increase his chances to 25%, while if the short stack were the weakest player, his chances might be as low as 2%.

What this means is that you can use your perceived edge and stack size to make an estimate of your chances at each final table you play. Instead of saying to yourself “I really hope I double up and win this tournament!”, you can say “well, I have an average stack, but it's a fairly weak table, so I think I might win this thing 15% of the time from here”. You can adapt this estimate as you get short-handed, too – if you get four-handed with an average stack against three very good players, you might win a lot less than 25% of the time, but if you get heads-up with deep stacks against a huge fish, you might win as often as 65-70% of the time.

This should help you stay more level-headed and grounded in reality. It also prepares you for thinking more deeply about ICM spots and edges, because it keeps you in touch with what kind of edge you have on the table at any given moment. Obviously it's very hard to assign accurate values to your edges in specific spots, but over time you'll get a better handle on it.