Antonyms for the phrase "give one best shot" include not trying, half-hearted efforts, and lack of commitment. When someone is not willing to give their best shot, they are usually discouraged, unmotivated, and disengaged. Instead of putting their all into a task or project, they may quickly give up or go through the motions without any real effort. Half-hearted efforts show a lack of investment or interest in the outcome, leading to mediocre results. In contrast, when someone is committed to something and puts their best foot forward, they are fueled by passion, dedication, and a desire to succeed. This enthusiasm helps them to achieve their goals and to feel fulfilled in the process.