The more important question appears to be why it seems to difficult to follow the advice?

Personally, I'm well aware of the positive effects of drinking plenty of water, eating vegetables, exercising daily, and going to bed early. However, I buy myself a chocolate bar every day, love pizza, just want to unwind after a hard day at work, and still read Reddit late into the night.

All the healthy stuff has friction: a workout takes time out of the day, the veggies need preparation, while going to bed early means I'm missing out on fun or intriguing things that I would learn about otherwise.