Are the heroes/heroines from centuries before your story starts or are they in your current tale and you hint at their back story? How are myths and legends reported by your world's media/historical societies/officialdom (which can also include religious officialdom)?
How does your hero/heroine cope with being a living legend? (Would make it awkward to go to the shops at times I would have thought! Now I'm being a little flippant here but you get the point. Your characters would have difficulties most would never face to enjoy any semblance of a normal life at all so how do they overcome all that or come to terms with it?).
Hope you find some wonderful story ideas here.