I need help getting motivated to weight lift, again.?

I've been very self motivated when it comes to exercise for the past 3 years. However the past two weeks I have only been doing my running, walking, and lunges everyday. Usually I do crunches or weight lifting when I get home. While I'm out running I tell myself I need to weight lift today its been two weeks! but when I get home I don't do it. Uhhhh this is new for me so I don't understand. I've been really down lately because of stress, but that's not anything new. I'd take a break from exercise but that is a terrible idea because its almost summer, and prom, and seeing my bf after 8 months of long distance, and electric daisy carnival in june. So losing my results adds more stress! Anyway, I need help getting motivated because I don't know why I havnt been lately.