i have sat all day on many occasions. first eat a big breakfast. fuel for the body to create warmth. also keeps you alert longer. take your lunch and snacks with you. make a plan before though. example, if you say your not going to eat or drink till 10 then dont. then not till 3 . then dont. you'll stay sharper and more in tune of the area. cover your head good,most body heat is lost there. i wear an under armour facemask with a knit hat over that. since i started with the au mask,i noticed a big difference in staying warmer. next is hands and feet. keep them warm. also lower back area. also if your doing blind calling you can stay alert more. and you just may entice that big boy to come in.