If riding in the wind makes you more tired, take more breaks or longer breaks each time. There is no shame in taking more breaks. If your goal for the day is 20 miles, for example, do what you need to do to accomplish that before you phone your wife to pick you up. At the same time though, don't push yourself too hard since you're 75 (and still kicking ass). I don't know your current medical history but there are some where it may put you in the danger zone if you push yourself too hard.