Stronger than Yesterday

Britney Spears sure had the right idea when she wrote that song. Even though it's about not needing a man, the premise sure seems nice: "I'm stronger than yesterday, now it's nothing but my way, my loneliness ain't killing me no more..." This attitude encompasses who I thought I was when I was single. I had to rely on God and on myself; I constantly lived in a "suck it up" mentality, giving off the heir that I didn't care what people thought, and that I could take on the world.
Lately, I've felt anything but strong. I used to think it's because now I finally have someone I can open myself up to, and that my emotions are making up for lost time. But defeat just seems to come so easily. I've become pretty pessimistic--not getting my hopes up because I can't handle disappointment.
With all of the craziness of me passing out last week and doctors trying to figure out what is wrong, I've run the emotional gamut. I've done my best to trust in God, to surrender my worries to Him, but I fear that I've failed somehow. I'm left with a ball of nerves, a disappointment in myself, and a longing to be stronger. I think about Kelley McElreath, how she looked cancer in the face and used every ounce of her journey as an opportunity to provide hope to cancer victims. I see my dad, how his job beats him up daily but he comes home with a smile on his face. I want to BE those people. Not a weeping puddle of self pity and anxiety.
How does one come to this point? What can I do to be stronger? I am afraid to pray for strength, because in my experience God gives you opportunities to be strong...and I really don't want yet another test of my strength.
Any advice? I think that Justin deserves a wife that can stand on her own two feet. Just saying.