"With might and main" is a phrase used to describe the exertion of maximum physical or mental effort. Synonyms for this phrase include "with all one's might," "with full force," and "with great effort." Additional synonyms that convey the same sense of intensity include "with unwavering determination," "with unbridled passion," and "with relentless zeal." Each of these phrases suggests a strong sense of dedication and focus, indicating that the speaker is putting forth their best effort to achieve their goals. Whether one is engaged in physical activity, intellectual pursuits, or anything in between, these synonyms can help to communicate the importance of prioritizing effort and determination above all else.