If there are other people in the lift with you, try initiating some kind of game to take everyone’s minds off the situation while you wait for help. Encourage them to stay calm and keep things light-hearted, avoiding negativity. Confined spaces can be difficult to deal with when you think you are stuck, so avoid any confrontation or emotional triggers.
If you are alone, or prefer not to talk to anyone then keep yourself occupied by any means. Just don’t drain your phone battery.