I live in a pretty hot climate, but it’s only really unbearable at times due to shoddy building and bad urban planning. Even then, summer can be difficult.
I can’t imagine what it’s like on the equator, especially in dense urban centres. What’s Mumbai, Bangkok, or Singapore like at the height of the wet season?! How do millions of people function day to day?
Colds not too hard to deal with at all. As the other poster mentioned, when outside, the trick is layers.
Inside, it’s actually very easy to trap heat. Knowing where and how it dissipates in a house makes a huge difference, but it’s generally much easier to heat a place than cool it.
Layers are the thing I hate about the cold