These are some things I've learned which guide the way I think, and which I value most. I hope they are the most valuable things I can offer to you. Of course, they come entirely from others, who I've paraphrased or quoted below. (I'll reference at the bottom.)
There is more advice and knowledge than I can ever consume. Most of it is probably good and useful to some extent. Hence, choice and prioritization are even more important.
The way something is presented is often more important than its content. The most important part of the way something is presented is how long it takes someone to consume it.
Time is the most important thing I have: "it has been said that time is money. That proverb understates the case. Time is a great deal more than money. If you have time you can obtain money--usually. But though you have the wealth of a cloak-room attendant at the Carlton Hotel, you cannot buy yourself a minute more time than I have, or the cat by the fire has" (Bennett).
I’ll spend maybe a third of my life sleeping. Traditionally, another third working, but: "there’s a common misconception that work is necessary. You will meet people working at miserable jobs. They tell you they are 'making a living'. No, they’re not. They’re dying, frittering away their fast-extinguishing lives doing things which are, at best, meaningless and, at worst, harmful. People will tell you that work ennobles you, that work lends you a certain dignity. Work makes you free. The slogan “Arbeit macht frei” was placed at the entrances to a number of Nazi concentration camps. Utter nonsense. Do not waste the vast majority of your life doing something you hate so that you can spend the small remainder sliver of your life in modest comfort. You may never reach that end anyway" (Tan).
I try to guide what I do by this simple dictum: to do everything I do with intention. If one is happy to be average, it will happen. Being average is the default. Create, rather than consume. Consume with intention: don't watch TV, watch a show.
Last, I try to be mindful. What I mean by that is to be active in choosing what I think about, and to fight the defaults. Which is to say, for me, to be ego-centric. I like this mind-game from David Foster Wallace: "there are totally different ways to think about these [miserable, tedious] kinds of situations... [perhaps] the Hummer that just cut me off is maybe being driven by a father whose little child is hurt or sick in the seat next to him, and he's trying to get this kid to the hospital, and he's in a bigger, more legitimate hurry than I am: it is actually I who am in HIS way. Or I can choose to force myself to consider the likelihood that everyone else in the supermarket's checkout line is just as bored and frustrated as I am, and that some of these people probably have harder, more tedious and painful lives than I do." But the point is not so much what you should think, rather that you get to choose what to think, and especially that you can choose to be happy. Strive to be happy.
Arnold Bennett's How to Live on Twenty-Four Hours a Day.
Adrian Tan's commencement speech to NTU in 2008, "Don't work, be hated, love someone."
David Foster Wallace's commencement Speech to Kenyon College in 2005, "This is water."
Max Ehrmann's Desiderata.