Best of Luck
I am in a very similar situation. While I enjoy my current job, I have always been interested in running my own business.
Trust me, I have crunched the numbers and the potential to make a lot of money in this business is there... if the effort is put in. You need to start working on a business plan, if done correctly, you will set expectations and have a clear understanding on where you need to be on a month to month basis.
I would also recommend starting slow. I am still working full time and mowing about 7 residential and 1 commercial lawns per week.
This example below may be dreaming, but its definitely doable!
8 Lawns per day at $50 = $400
$400 per day x 5 = $2000
$2000 x 27 weeks (rough estimate) = $54000
Expenses (Considering that equipment is paid for)
Gas - $6500
Insurance - $700
Advertising - $800
Misc - $5000
End up with 41K