You agreed to come. You can't back out now! They backed out of the deal the day before they were due to sign the contract. She backed out of organizing the fund-raising.
Ever since the secretary left, the letters in my inbox have started to build up. We tried to build his confidence up. She does exercises daily to build up her strength. I've been putting $50 aside every month in an attempt to build up my savings.
I wonder if you'd have less back pain if you built your core up. I'm trying to build up my leg muscles so that I can run even faster. They had to build up their fortress to protect against attack.