“Define success on your own terms, achieve it by your own rules, and build a life you’re proud to live.”
Who said it: Anne Sweeney, former president of Disney Channel
In this case, “terms” are rules or ways of doing things. For example, “We will do the project according to Jeff’s terms” means we will do the project the way Jeff tells us to do it.
The phrase “Define success on your own terms” means that there is not one definition for the word “success.” Success has a different meaning for different people. For some people success might mean having lots of money, while for others it may mean building a product people love.
The quote tells us that we should decide what success means to us on a personal level, and then work towards achieving it so we can be happy and proud of our accomplishments.