This quote highlights the importance of having a balanced and realistic attitude when pursuing goals or tasks. "An attitude is whatever is convenient won't accomplish very much" suggests that adopting an attitude of convenience or taking the easy route is unlikely to lead to significant accomplishments.
On the other hand, "an attitude of whatever it takes is impossible" recognizes that it can be unrealistic or unsustainable to adopt an attitude of complete, unwavering dedication that disregards all other aspects of life. This part of the quote emphasizes that expecting oneself to do "whatever it takes" without any limitations or boundaries can be impractical and even detrimental.
Overall, the quote encourages a middle-ground approach. It suggests that while convenience alone may not lead to significant achievements, it's also important to maintain a balanced and achievable attitude. This means being dedicated and determined but also recognizing one's limitations and the need for a sustainable approach to success.