Lethargy, Lack of interest. For this.

Hello i am male, with height of 165 cm and weight 68 Kg. Since 6 years i am suffering from following problems. I am feeling very lethargic, no interest in doing anything. I tend to sleep while in at my work and do not get scared by prospect of loosing my job.i have no interest in Even enjoyable things and when i do try doing something i find it hard to complete the task. Also feel confused time to time. I cannot do simple everyday task without messing up like making recipes , finding addresses. I also forget about what i was thinking a minute ago and find it too tiresome/ indeferent to even think and remeber the thought. I also have some physical symptoms like weird tight / tense feeling in head, weak heart feeling and lightweight body feeling like i am made up of cotton balls. This symptoms are accompanied by general body weakness and loose muscles. My speed of walking has also slowed since i feeling unwell. Can some please guide me what could be the reason for this.