What are some good foods that I can eat for break-fest?

I'm trying to diet but lately i have been skipping breakfest since i can't find anything healthy or good i can eat. I'm still a teenager,17 and all my life i have been drinking banana chocolate milkshake every morning. I stopped since it makes me wanna use the restroom within 5-10minutes after drinking it. Anyways what is something healthy and good that i can eat that will help me gain muscle or even make me feel really good!?