Believe that God's plan is best (in all things, of course, but in this case, specifically in regards to my singleness). broken down a bit, this means:
...my singleness is His plan! There was no "oops" about this. He didn't forget me, overlook me, or let me fall through the cracks. My life wasn't an accident, and neither are the events in it. If I have "the gift" of singleness, it's because He has given it to me, and right now that is the best way to make me into the woman He wants me to be.
...and, His plan is better than anything I dream up. And even though I knew that was true, I didn't always feel that it was true. I wish I had. It would have made life easier. It would have made going to bridal showers and baby showers and weddings and Bible studies (where everyone talks about their husbands and children) easier. Believing His plan is best means that this thing in my life is best for me right here, right now. Not having a husband and not having children at that time was best for me.
...and, I needed to tell myself this often. Every morning, every evening, as often as I needed to be reminded (which was sometimes more than just twice a day). When I'd go to those showers and those weddings and those studies, I needed to be realistic about the context I was going into, what my selfish reactions would be (why not me?), and what God was calling me to (that I rejoice with others! that I believe He is all I need! that I look for practical ways to serve! that I focus on others who are feeling marginalized! etc). And honestly? My heart often looks for ways that God is holding out on me, rather than reminding me of how he has blessed me so abundantly. So. It's always good to tell myself these truths (not just when I'm on my way to showers).
I found it helpful to tell not just myself these truths but to share these things with others who asked. In the Christian community, the majority of the women I was surrounded by were married, and were married young, and so of course they wondered how I got to be 30 (and then 34...and then 36) and still not be married. Did I want to be married? Yes! I would tell them. But, God had a different plan for me at the moment (a better plan for me), a plan for a life that was just as good and as full (and as difficult*) as the life of a married woman. It was a life that I was to embrace.
p.s. don't ever say that one is harder than the other. They're both hard in their own way, and God is just as good in each.
so ummm....this post was harder to write than I expected. My disclaimer is that I found these values to be most helpful for me. There are other women out there who have way more experience and wisdom in this area than I have, women who speak at conferences and write books and cover this topic a lot more comprehensively than I do.