How do you decide if you should do something 'big'?

First be content with doing the 'small and mundane', because even if you do the 'big', once you do that, life may still seem 'small & mundane'? And then once people get semi-established, I wonder if it's hard to pursue the 'big'...like now that I'm now I'm moved out (well, I still need to go through a bunch of junk back home), how would I ever even consider doing the 'big', unless I strive for the 'big' in the middle of the seemingly mundane life...and yeah, so maybe I'm on my way to being 'established', but, whatever that means, ... 'established' as a single individual who has possibly lived 1/3 + of her life, and possibly who will have a new kitten next month? Will that be my 'establishment'? What happened to my big 'dreams' of the past? Now here I am - all grown up, and in a time of transition. Now what...