I have co-owned a gym for over 35 years. We started small and grew into a large center with more employees. All said and done it is a high investment, low return business. The hours are really long as most clubs open early and close late. You have to know what your market is before you buy a club or open one.
You should get your landlord to do the fitout and repay him with a higher rent. That way you both claim what you paid instead of borrowing to do that fitout and claiming only the interest and something like 10% per year. You will have to own your own home before banks will finance you. You can do an interest only deal until you are making a profit. You can lease your equipment but make sure you know which equipment to buy or lease. All equipment is not the same.
You will need sales people and someone who knows about marketing. There are successful clubs out there so go and see what they are doing. Sometimes they will tell you what you need to know. Join IHRSA and get back issues of their magazines. Lots of good info there. Attend the IHRSA conference and tradeshow in San Francisco which comes up soon this month. You can get heaps of ideas about running a gym successfully.
Our equipment cost over $1,000,000 and has to be replaced or upgraded from time to time. Perhaps having a smaller club with good equipment and instruction might be better than having a large gym with huge overheads. Aerobics usually doesn't make any money. Do what you are good at. If it is bodybuilding then set up a good gym for that instead of trying to be everything for everyone. A 5000 square foot well-equipped gym might make it compared to huge clubs that cost too much to run.
Location is important as is software and everything else in this business.
If I had $30,000 I would open an ice-cream store! Arnold never opened a gym because Joe Gold told him there was no money in it. He was told to invest in real estate. Good advice from a good gym operator.
Good luck.