Like many people here who are over 50 I make no conscious concessions due to my age. Last year while riding in Uzbekistan where daytime temperatures routinely hit the mid 40C I noticed no difference in my ability to withstand heat compared to previous hot weather rides; Egypt's Eastern desert, India's Thar desert. Both of those rides I did when I was much younger. The only difference now is that my average speed had dropped a little and going uphill requires lower gears, I can live with both.