as if (one's) life depends on it

With maximum, possibly desperate, effort or energy (i.e., as if one is at risk of losing one's life if one fails). The boxer started the third round throwing punches as if his life depended on it. This project could very well determine the future of the company, so start working as if your lives depend on it! A: "She's been working on her thesis as if her life depends on it." B: "Well, her chances of getting into a Ph.D. program do depend on it."