I got this idea from the "5 Second Journal".  It suggests starting the day with a quick assessment of how energized about the day you feel, noting why you feel this way, and then prompting you to write down one way you can feel more energized.

For example: 

Today I feel: "meh"

Because: I feel overwhelmed with everything  I need to get done

I can feel more energized by: taking 10 minutes to write a list of what has to happen and prioritize/delegate/eliminate items

This is an effective way to energize your day, and also learn what energizes you and what drains you, so that you can plan a mix of activities to maintain a higher energy level.