I don't heat it to 98 everyday. I do ALWAYS have a bottle of QF in my pocket or fannypac anytime I'm at work. I've practiced enough to know that I can go from pocket temp, around 80-85, to body temp, 95+, in around 30 minutes with only my body heat. Read the substitution guideline linked to in my signature for the graffic details on crotch and carry.
Hope that helps. N2