I'm 72 and I have always ridden with distance as my goal, rather than speed. When my wife (a few years younger) and I go on vacations, we typically do a fully supported 6-day, 5-night tour of 50-60 miles per day. We have also done self supported rides of similar daily mileage. It's when we're home that we are doing the "training" rides, about 50 miles per ride, as many days per week as we can manage, in between appointments, errands and home projects. We do this so we'll be in shape for our bike vacations. If we've been getting 3-4 rides in per week, we may put extra effort into some ride sections in an attempt to boost our average speed, or climb some extra hills, but we don't get obsessed over it. At the end of just about every ride, I expect to barely make it up my driveway, completely exhausted, and just like magic or something, that's what happens. I don't know how to train any differently.

But I guess if your goal is to go faster for a shorter distance, that's okay too. Umm, except that essentially, you're training to get somewhere in a hurry. Why are you in such a rush? Nevermind. None of my business.