Where is the drawing line between living a life that reflects the type of person you are, and using this as an excuse not to improve yourself?

It appears to be a common thing for people to say that you need to accept yourself for the person you really are, and I’ve lived up to this myself personally, at least in my own mind. However, there are also a great deal of people who tell you to try new things, not to be afraid to take a chance, and by challenging the way you think you can improve your own life and happiness. I’ve taken this advice too, where sometimes I was glad that I’d done this, and other times I’d regretted the decision.

What is the drawing line here? How do we determine which chances we should take or not, and when we may need to do this?