"Si Dios Quiere" is a phrase you'll hear frequently in the Dominican Republic. It means "if God wants it," and it's tacked on to the end of statements, as in "we'll see you at seven, if God wants it." Perhaps sometimes, it's simply a colloquialism—something people are conditioned to say without much thought. But there's more to it than that. It's a phrase that demonstrates one of the pillars of Dominican culture: a humble realization that so much lies beyond our control. It's a mantra that acknowledges this several times a day.
It reminds me of a maxim often attributed to St. Ignatius Loyola* that goes like this: "Work as though everything depends on you; pray as though everything depends on God." In a way, then, there is a paradoxical message here. Have the humility to acknowledge that we aren't in control, but don't for a moment use that as an excuse for complacency, mediocrity, or, at worst, apathy. What a joyful, patient, and grateful way to approach life. I think that's part of what makes Dominican communities so strong.
* There is informed disagreement as to whether St. Ignatius actually said or wrote this; however, the sentiment is in keeping with other quotes and lessons more definitively attributed to him.