build up

verb

1. enlarge, develop, or increase by degrees or in stages"build up your savings"
2. form or accumulate steadily"Resistance to the manager's plan built up quickly"
3. prepare oneself for a military confrontation"The U.S. is girding for a conflict in the Middle East"
4. bolster or strengthen"We worked up courage"
5. change the use of and make available or usable"develop land"