OP, I used to be like that. I wouldn't drink much. But a couple years ago I was on a charity ride on a very hot day. With 10 miles left I realized I felt a little chilly and wasn't sweating anymore. Panic set in, I knew the next day was going to be very painful. Ever since then I drink constantly, refilling my 2 bottles 2 and a half times on a 40 mile ride. Get into the habbit of taking drink often, even if it's just a quick sip, it's better than nothing.