I often post mantras on my Facebook page.

One of my favorites is “Everything happens for a reason.” I try to remind myself of that when something negative and unexpected happens in life, even if I don’t understand why at the time, and there is a reason or purpose and in the end it will come to light.

That happened for James Costello. You may not recognize his name, but you’d probably recognize his face. Costello was supporting a friend who was running in the 2013 Boston Marathon. He was severely injured when two bombs exploded near the finish line.

A photographer captured Costello staggering through the streets with his clothes shredded and his legs burned. In the wake of the blast, that horrific photo became one of the most widely-viewed images around the world.

In an appearance on the “Today” show in December, Costello said that being injured in the bombing was a blessing in disguise because it led him to meet Krista D’Agostino, who was working a six-week stint as a traveling nurse at Spaulding Rehabilitation Hospital.

“One thing that she hates that I always say is I’m actually glad I got blown up,” Costello told show co-host Savannah Guthrie. “I wish everyone else didn’t have to, but I don’t think I would have ever met her if I didn’t, so I’m pretty happy.”

Costello proposed to D’Agostino eight months after meeting her at the rehab center, and they tied the knot Saturday in a beautiful wedding donated by local businesses.

In a Facebook post, Costello wrote “April 15 was one of the worst days of my life. I soon wondered why and for what reason this happened. I now realize why I was involved in the tragedy. It was to meet my best friend, and the love of my life.”

As I said, everything happens for a reason.