Have I correctly used ‘too smart to study’ and ‘just need’ in the sentence? Is it acceptable that I put ‘word hard’ and ‘persevere’ together even if they suggest the same thing?

Have I correctly used ‘too smart to study’ and ‘just need’ in the sentence? Is it acceptable that I put ‘word hard’ and ‘persevere’ together even if they suggest the same thing? Should I say ‘need not be’ or ‘do not need to be’?

We (need not be, do not need to be) too smart to study, but we just need to work hard and persevere.