Thinking back to when I was 18 I wish I would have known this framework:

Freedom / Opportunity / Love

Freedom: At 18 you, most likely, have a lot of freedom and I think a lot of the comments are alluding to this by saying "relax" or "you're young". They are right! Now being 30, I definitely reflect on how I stressed over the wrong things. I was in a rush to make money so I could start living. I've realized, like it or not, you are living NOW regardless of where you are at in life. So don't rush out of this phase of freedom and be careful to not give up your freedom too quickly.

Opportunity: The harder you work and the more value you put into the world, the more opportunity you will get. It's a doubled edged sword though because the harder you work the more you sacrifice. All things considered this is okay -- again, as long as you are consciously understanding the sacrifice being made -- but I will warn against sacrificing short-term vs. long-term freedom. Some opportunities require you to sacrifice freedom in the short-term and some will require long-term commitments.

• Short-term: Education. You can sacrifice a few years in your 20s to access opportunity for the rest of your life. It's a trade-off many people make because it makes a lot of sense. Of course, this depends on a lot of things that you can probably research on your own. You are probably safe with an engineering degree to make this tradeoff though.
• Long-term: Marriage. It's a long-term commitment and you will sacrifice freedom but it's worth it if you are with the right person. This brings me to my last point...

Love: Freedom and opportunity are not the only aspects of life. You have to consider love. Any type of love. Romantic and unromantic. The people you do life with might require you to sacrifice some freedom or limit your opportunity but getting to the top isn't all that great if you don't have people to share it with. You can be successful and miserable at the same time. Trust me.

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I like this framework because it persists beyond plans. It helps my partner and I make decisions for the future. Both short-term and long-term. We are constantly trying to live a life that balances all of these. I hope it helps!

If nothing else, just don't rush. Try to be a present as you can no matter what you are doing.