I started out as a LCO because I lost me job and couldn't find another. I am making more money as a LCO than I did at my last job and I like being my own boss. However, I have no benefits. I do like taking time off during the winter.
I have been able to expand because I put almost all the money made back into the company. If you choose this route, your living will be pretty poor for a few years. Many LCO's run their company like a hobby. If you run it like a real business, you can do ok. I make between 45 and 60 thousand net a year. It is not great but I have potential of increasing it as I grow the business.
I started this when I was 57 years old. I wish I started when I was younger. This is my 3rd company I have owned and the experience I gathered along the way has helped be successful in lawn care.
I am amazed at how much money there is to be made in lawn care. It is very hard work. I work from 8:00 am to close to dark 6 and sometimes 7 days a week during the season. For the hours I put in I probably don't do very well.
If you choose this route I give the same advise my mentor gave me: Get your insurance and licenses and pay your taxes. Otherwise you won't be in business long.
If you choose diesel mechanics I think you can also do well. If you have business ability you can start your own shop. If you don't have business acumen then work for someone else no matter what you do.
I tell people I haven't worked a day since I started this business. It is all play. Do what you like the most. You are only 20 years old. You can start over several times at your age. Most of us have.