In act 4, what compels juliet to agree to the friar's desperate plan?

Juliet strongly feels that this is the only possible way she and Romeo will be able to escape from the bondage's of past, and maintain a loving, healthy marriage once they've escaped from the house of the Capulet's, and Montague's. She also has to be married to her cousin in less than a few days, so it puts her into a frenzy to try an idea that may bid her and fair Romeo joy.