When entering the poker tournament make sure rewards for winning / placing justify the effort that will be spent playing. If you “win” $3 for coming 5th in 2,000 player tournament after 4 hours, then in reality you’ve just wasted your time.
As well as making sure you “want” to win, make sure you have time to win. A large tournament will take a number of hours, so there is no point entering if you are unable to see it to its conclusion.
Understand that when you sit down to a tournament, you are highly unlikely to win. There are so many variables / all-in’s / bad-beat opportunities that you are going to have to ride your luck to win. That said, half of the field can probably be discounted straight away, so you HAVE got every chance of cashing in.