In the 70's I routinely packed 60+ lbs. While that hurt, I didn't know any better. Since then, I have learned a lot and the technology has improved greatly.

Now my base pack weight is 20 lbs before water and food (1.5 lbs a day) resulting in around 30 lbs at the start. This gives me all I need to be comfortable in most any weather I am likely to encounter: temperature 25-90 degrees F, and rain, snow, and winds to 40 MPH, all of which I have experienced during the summer in the high country of Utah, Colorado, Idaho and Wyoming. Also Belize and Mexico.