How do you stay postive after another bfn

I'm really sad. It's another month of 'No' - we're trying for a second baby and i thought since my first was a surprise that my second planned would be easy. I was sadly mistaken. There have been obstacles i won't get into but from those of you who have been at this longer than we have - how do you stay positive? How do you not give up? I've been in tears most of today with the realisation we missed this month....again