I have frequent stomach upset...due to which i feel lathargic..what should i do to avoid..?

Assess the cause: The first step is to find out the cause of the stomach upset! if there is a history of ulcers then assessing for h. Pylori infection and treating that may help, plus acid-lowering medicines. If there is reflux, then also modifying your eating habits, taking Gaviscon before bedtime, and elevating the head of the bed helps. There are many other possibilities your doctor can help you with.

Agree with Dr. R: If you are overweight losing weight will help, Have a healthy diet, exercise 30 minutes/day, drink plenty of water, have safe sex, no tobacco alcohol weed or street drugs. For nutrition: http://www.choosemyplate.gov/.