Three main meals with three snacks in between are the ideal course for the day. Avoid taking a large meal after hours of not eating anything.
Even if you walk for 15 minutes a day, you will feel an extensive energy boost. You can also improve it by increasing your time of physical activity.
If you want to get more energetic, try losing some fat. You can take a calorie-deficit diet and do a physical workout to become more active by the day.
Make sure to keep your bed timings constant and don’t take naps in the daytime. Switch off your devices before you go to bed.
Stress takes up a lot of your energy. You should introduce some techniques for relaxation in order to get rid of the stress.