But you must study the type of food you eat, if it is not nutritious enough, you may not be getting the required energy. Make sure your meals are not mainly junk food, consist of all types of nutrients - carbohydrates like whole grains, vegetables, fruits, proteins like dals, milk products, fish, chicken, etc. Add some nuts in small quantities and water. The changes you make in your food do make a great deal of difference in your energy levels.
You could also add light exercises to your everyday plan, so that it boosts your energy levels. Forgetfulness could also be a function of having too much to do, with no time to relax and for recreation. If you work hard at it, you will not forget things that are important. It is a matter of keeping the most important things in priority and making a list of those things that are not.