Pace yourself. Slow and steady wins the race. When I was younger, I could run balls to the wall 12 hrs or more per day, every day with no problem which was great for working construction. By the time I hit my mid 30's, I'd been working in factories over a decade so when I'd start a construction job and try to go at my old speed, I'd burn out hard after about 5 or 6 hours. An older friend worked with me on a roof one weekend and changed my perspective and he was right. This past Saturday was a real scorcher here in Indiana. I spent all day (12 hrs) milling a 10' oak log in half (just under 60") and getting the halves winched up on my trailer to haul to the mill. I ran through over 2.5 gal of fuel through my G660 running a 42" bar. After every tank, I sat on the tail gate and took a 10 min break and normally drank a bottle of water. Sharpened the chain every other refill. Drank over 1.5 gal of water and didn't have to take a pee until late Sunday morning. I was a little stiff when I woke up on Sunday, but could have easily gone out and continued working if I had needed to.