Every time I hike on my favourite canyon, I see people running up the steep hill in hot Californian sun. And every time one of them passes by, I wonder how fit they must be to run up this hill, and feel a bit bad about myself being lazy. And in 95% of times, the moment I turn the corner, I find that same person walking and panting and drinking water. I just realized on my hike yesterday what an important philosophical lesson it is: Never ever envy people. Because you never know what their situation will be just around the next corner.