Everyone nowadays is spoiled by air conditioning. When it's hot, wear less and lighter colored clothes. When it's cold, put on more layers and a warm hat. For heat, when I used to go backpacking, I always kept a little backpacker's towel with me. It packed the size of a small disk, but when you got it wet, you could put it around your neck to cool the carotid artery with evaporative cooling. Those towels are very cheap. Any towel or wet rag will work. A more high tech version is a Sharper Image or Arctic Air Neck Evaporative Cooler. Works best if put in the refrigerator for 30 seconds to supercool before using (at least for the old Sharper Image one). Also helps to drink cold liquids in the heat and hot liquids in the cold. If it's hot and you have electricity, cool water, juice, soda, etc. in the fridge to drink when you get hot. When you're freezing, try hot cocoa, hot coffee, hot tea, etc. If it's hot, stay in the shade and do more active activities when it cools down (morning, evening, night). If it's cold, keep active to keep warm but try not to overdo it by sweating which will make you cold. Acclimating to the weather doesn't just involve getting used to the temperatures. Your habits have to adapt to make it easier to handle the situation.