What would be a good workout routine for me?

My work schedule is crazy during the summer and fall and slows down in the winter. During the busy time I usually work 12-15 hour days and then in the slow seasons usually only 10 hour days. I am wanting to loose 30 to 40 lbs and I need help. I have started trying to eat healthier and snack healthier at work, but I know that i need to include some form of exercise. I have a treadmill and i have some workout DVDs but I get bored with them and then I just quit doing them, plus i don't feel like I am getting any results. I love my preset "paths" on my treadmill but i don't feel like i am loosing any weight. What could i do to help me reach my goal?