I run a landscape business here in Texas and have since I was let go from Dell in 2001. Overall, I would say the money is a lot better at times then working at an employer. You can really start adding in revenue if you service commercial properties with year round contracts. A good year was/is >$150,000 in gross revenue while hiring some contract labor (which is the biggest expense). I also run a computer consulting business (better profit) on the side which brings some money also. The main problem with a business is that you are always looking for new customers or trying to get existing customers to pay. I still go and work the properties everyday or leave labor while I do service calls. It does get old to be in the 100 degree heat for 12 hours or more.
Unfortunately, you usually stop enjoying something once you are getting paid to do it and have to meet some sort of commitment.
I have used this for years. It is great to test a machine so you don't have to spend time swapping parts. It gives an answer fast.