Everybody picks up bits of insight and inspiration during their journey. Here's a short list of what I think makes for a fulfilling life.
This is in no particular order, and I occasionally add to it as I see fit.
Most of this falls under "what would I tell my younger self" category.
What you don't do doesn't matter (hat tip to CG)
There is a simple formula to a happy life, a life a that moves forward in creativity and passion, a life that builds good over time, and a life that keeps stress and anxiety at bay.
Spend less than you make. Create something every day. Think big thoughts. Strive for more than you think you are allowed to. Walk to the beat of your own drum. Fail often, because that means you tried. Find the good in people. Help when you can. Keep a clean house. Repeat.
Life does not have to be complicated. Strive for simplicity, for then you can stop and watch the sunsets more often.
Growth can't happen along with comfort. It's okay to be comfortable in order to relax temporarily, but know that it is hindering growth. You have to feel some resistance. There has to be some urgency. You need those in your life that will push you.
STOP CONSUMING, START CREATING. Especially in the world of social media and 24 hour news cycles (who's job it is to hook you in so they make money on ads ... never forget this) it is far better to unplug intentionally and focus consumption into tiny little pockets once or twice a day. I aim for ten minutes total, and that's local news, national news, international news, and social media with friends.
People can transform.
You can change how you live, how you eat, and your physical and mental health through deciding to. It may be hard, it may take a long time, but if you want to change any part of your life, habits, or personality, you can (at any age). The key is deciding to do it, not just hoping for it.
Time spent wasted is the biggest detriment to a fulfilling life.
By "wasted time" I mean living without larger goals, hopes, dreams, and purpose.
By "wasted time" I mean not trying to improve yourself in incremental ways continuously.
By "wasted time" I mean hanging out with people (or working for people) that don't add anything beneficial to your goals and your life. People that bring you down or try to put you in a box or control your thoughts or your time or "tell you how it is" are vampires that should always be kept away from. Run. Fast. They are trying to define their lives based on controlling you.
Time spent thinking, dreaming, wandering, and planning is never wasted time.
Time spent loving family and laughing with true friends is never wasted time.
And time spent creating is the best time of all.
The biggest thing to avoid in life -- treat it like a deadly virus, so you're nowhere near it -- is debt.
The biggest thing to embrace in life -- run to it, seek it out, or build ways to surround yourself with it -- is optimism.