We are a 2 person start-up and have been through exactly the same mental re-adjustment. We started by defining success as 6 figure investment and 7 figure exit. We're now happy to define it as a positive trend: maybe 5 figure investment - or bootstrap sales - and a sustainable business or 6 figure exit. This adjustment comes from seeing how hard it really is to sell a product, no matter how good, and a belief that what really matters is the trend not absolute outcomes, so long as you are constantly learning along the way.