What can I eat before my workout to keep from crapping out?

Hi! I am pushing 40 and still work out pretty hard 4 days a week. Typically an intense 30 minutes on the elliptical followed by 30 minutes of weight training. Pre workout I typically have some yogurt with creatine and some nuts. Post workout, a protein shake. Unfortunately, I seem to shoot my wad by the end of my cardio. I am dragging through my weight routine. Any fuel suggestions?