You would need to do a Feasibility Study to determine whether or not your business would be viable and successful.
Who would you need to hire, licensed professionals? How would you attract them? How much would you pay them? Is your pay competitive? How much would you charge clients? What would your rent or mortgage be? Taxes, expenses like insurance, cleaning, utilities, phones? Advertising costs? Business expenses such as letterhead paper and business cards? Website setup? In the end, would income cover costs?
What are the demographics of the area in which you hope to set up your business? Who would be your Target Market--the elderly, college students, whomever? Are people in the area affluent enough to pay for your services? Will they seek out your services? How desirable is the location of your business--is it close to a center of activity, or off the beaten path? Who's your competition? Will you attract enough patients to fill the therapists' schedules, or will there be empty hours (thus no income)? How many empty hours/day can your business handle?
How much money would you have to have, or borrow, to launch your business? Is a bank willing to give you a loan? [if they don't think your business will be viable, they won't give you a loan]. Do you have an adequate emergency fund?
The above are just a small handful of questions that are part of doing a thorough feasibility study. Good luck to you.