Antonyms for the phrase "am on par with" include falling short, lagging behind, trailing, inferior, substandard, and underperforming. Whereas "am on par with" suggests equality or similarity in performance or status, these antonyms imply a lack of such equivalence. They indicate a lower level of attainment, capability, or achievement. However, it's essential to understand that using antonyms is not always negative. There are instances where falling short or lagging behind could be an opportunity to improve, learn from mistakes, and work towards achieving a higher standard or level than before. In such cases, antonyms may serve as motivators.