Feeling tired all the time. Situation.

From last few years most of the time I feel sleepy and tired. I feel as if am not having the strength and stamina to do my daily work. Even if I go for shopping or go to work,I feel completely exhausted. I feel as if I am not having much strength in my hands and legs as I used to have. From last 5 years I am self employed. Before starting my business I was a banker and used to do a desk job. I am having lots of tension,I think, though not sure that I am in depression. Just want to inform that I left smoking 5 years back and been drinking regularly. I don't do any exercise.I am also working on a new project which needs lot of travelling & physical work but due to my existing health condition I am not able to cope up with it. After having breakfast or lunch I feel very tired that's why I eat less. I am not diabetic.Request suggestions to tackle and overcome this kind of medical situation.