Meaning of work up

1. She had to work up the courage to ask her boss for a raise.
2. I need to work up a sweat at the gym before I feel like I've had a good workout.
3. The singer had to work up his vocal cords before the performance.
4. It took weeks for him to work up the nerve to confess his feelings to her.
5. I need to work up an appetite before I can eat that huge meal.
6. She had to work up a plan before approaching her team with a new project idea.
7. It's important to work up a good lather when washing your hands to kill germs.
8. The hikers had to work up their endurance before attempting the difficult trail.
9. He had to work up his strength before attempting to lift the heavy weights.
10. The comedian had to work up some new material for his upcoming show.