I had my heavy breakfast at 7.30 am morning and my regular tea at 9.30am After standing for long 1.30 hrs at site in hot afternoon when I came back to office at 12.15 pm I started shivering and body was shaking. Then I had my lunch and took few deep breaths and then I was received. Rest of my day was tired.. What could be the reason ? I am physically very active, I do workout ( gym everyday) and 8 km walk everyday.