I hope to have a lot more "lifetime" left, so we'll see... [8D]

To come more closely to answering your qustion though.. for me, it's getting above 185 or 190... I realistically only expect to see one or two of them in my life, considering where I hunt -- if that. And then being able to put it all together, to make it happen... One of those would definitely be a "buck of a lifetime for me."

So, to answer your question in general... I think it would be looking at your local herd, figuring out what is among the biggest in your area, and hoping to take one like that before you die.