“Don't say yes to everything. No is also an answer, and it can be a full sentence.”

“Success is not final, failure is not fatal: it is the courage to continue that counts.”

Often credited to Winston Churchill · Churchill never said it; Quote Investigator traces the idea to a 1938 Budweiser beer advertisement ("success was never final and failure never fatal. It was courage that counted") and finds the Churchill credit only from the 1960s.