I know what you mean about cleaning up the diet. When I ate lean proteins and "clean" carbs and veggies and drank nothing but water and worked out in the wee hours of the morning, I had an amazing natural energy that had me feeling I could take on anything.
Now (you think one would learn, eh) I'm slow to awaken and hit peak energy at around 11 am and it lasts until about 1 pm.
I think they key, at least for me, is feeling a sense of accomplishment, whether it's working out or doing well on the job. Any of those types of things will definitely keep me bouncing.