tldr: exercise, learn to cook, and start saving some money (keep your expenses low as long as you can)

I know a lot has changed since I was 18 but if I could give myself some advice to get a better start in life on a second try, here are a the first things that I would share.

1. Learn to take care of your body, it's the only one you get and it is much easier to work on your fitness and health when you are 18 than when you are 30 or 40 or whatever. While you have free time, this is a great time to learn and practice some good habits that you can carry with you for the rest of your life.

Two main ideas here:

• Find some kind of movement exercises that you enjoy doing and can make a routine of. You don't need to be an athlete or anything. It could be a daily walk, yoga, jogging, weight training, climbing, cycling, sports. For sports, I would look at things that are easy to keep up with as you get older, typically things with less structure or equipment requirements. For example, American football or volleyball might be harder to manage than tennis/pickle ball or indoor soccer/football. Don't make it a chore; you don't have to be great (or even good) at any of it, just find something that you want to keep up with. I know a lot of people also make connections with other people in some of these places (like climbing, cross fit, and sports gyms) but those also tend to be more expensive options.

• Learn to cook (if you don't already know how) and try to build a short list of reasonably healthy recipes that you enjoy and could live on every day, if needed. Try to focus on simple things to start, like eggs or oatmeal for breakfast, healthy sandwiches or wraps for lunch (try to minimize processed meats or peanut butter), for dinner maybe pastas, casseroles, salads, roasted vegetables & potatoes.

Try to come up with things that are quick and easy to make and especially things that can be made from staples that last a long time in the pantry or fridge. For a lot of people, planning, shopping for, and preparing food every day is a major challenge once when added to a job, school, or family. However, if you have a reliable list of foods that you can repeat without much effort, that takes away a major point of stress in your future life.

2. If you have a good relationship with your family, take advantage of this time to minimize your expenses and get some savings started. A lot of people are in a rush to move out and "start" their adulthood. If you are in a bad family situation, that may be the right move. If things are good, maybe get a low stress part-time job to earn a little income and get some experience.

For me, a big part of "low stress" is know that you can walk away at any time because you have a safety net. In my case, I can't quit my job because my family needs the income, which makes stupid things stress me out more than they should. However, when I was a teenager working low wage retail and fast food jobs, they did not stress me out because I knew I could walk out the door at any time without caring. From the outside looking in, my current job pays much better and is much more chill than working retail but I was way less stressed flipping burgers while living at home as a teenager.

The biggest "mistakes" I made after I graduated high school were eating a ton of fast food while going to college, dropping my gym routine when my parents canceled our membership when I was 20, and rushing to move out with my friends about the same time. The result of those things caused me to get fat and deeply in debt in my 20s and it took me all of my 30s to get back to even. I was probably around 35 when I got back to anything close to my high school graduation body weight and around 40 before my net worth went positive and I started any meaningful retirement savings.