How do you know if you're a good parent? There are some markers along the way to give you an idea of your grade -- such as whether your kids are good, caring friends; whether they work hard in school; and whether they are supportive members of the family.
Did you notice that McGonigal's talk is titled, "The game that can give you 10 extra years of life"? It doesn't say, "The game that will give you 10 extra years of life." There's a big difference between "can" and "will."