Cats are not self-conscious - if they want love, or play time or food, they ask for it.
Great joy can be found in simple things - pettins, gooshy food, scratches on the belly or behind the ears, playing with the laser pointer, or straws, or plastic bags or plastic bottle caps or empty cardboard boxes.
Cats can sit still and just be for extended periods.
Cats are always in the moment - they don't worry about tomorrow, or how much work there is to do, or what so and so said.
Cats let you know how they feel - annoyed tail, angry hiss, happy purr, etc. There's not much guessing about how a cat's feeling at any given moment.
Cats shed. A lot. (I know it's not a particularly profound life lesson, but it is something I've learned.)