I got into the game late at 49. Due to chronic arthritis, I have never been a high-volume cleaner.
Started with a Mytee Portable, two heating elements, two three-stage vacs. It cleaned wonderfully, but what a pain it was to only work with 10 gallons at a time. After 2 years, I had determined that it was way too much work to operate this way, and right at the end of my second year, the solution pump tanked ($1800.00) and was determined that if I fixed it, I would get out of the business, fix it and use it for personal cleaning only, or, see if the bank would give me a loan for a truckmount and all the necessary goodies. They did not bat an eye and approved the loan. In December of 2011, I bought a Saphire Scientific 454, my only truckmount. Low volume and just rolled over 1,000 hours. (25% of my jobs are low-moisture).
I will be officially an antique next week, hitting age 65. My health has tanked the past two years, and I have throttled back to just one job a day. If it has a major break, I am retiring the machine and the business. My first water pump from the water tank to the machine made it 8 years. I now replace a water pump every 6-8 months. It eats them. I keep a new one with electrical connections pre-set for a quick same-day swap in case of an emergency. Otherwise, the unit has been a champ!