Hello, Yolander. Love your current profile picture! The motivation can be your son! If you make a healthy lifestyle your goal, rather than just the weight loss, just think of the immense benefit to your son in the long run. I have found that my kids are more health conscious when I am. We lead by example. You have the benefit of your son still being an infant, so when he's ready for real food, you should already have that healthy habit established.
I say this all the time, it seems. The most useful thing I have found to get me motivated to get my 25-30 minutes of cardio is planting the recumbant bike in front of the television. It makes the time go by so much faster, and the feeling you get from making healthy choices far outweigh the instant gratification of unhealthy ones.