Best way to do it is:
1. download a template from here.
2. download a sample as close to what you have in mind.
3. study the sample to see how it has been done.
4. start filling up the template.
5 leave exec summary to be done last.
6. wherever you get stuck put some identification tags (e. g. @@@@@) and go to the next item.
7. write real answers, don't gloss over or omit.
8 in a notebook keep noting items you get stuck with, or could not satisfactorily write about or had to skip. then later work on them.
9. pay special attention to the financial part. overestimate expenses and underestimate income. overestimate time requirted for various things, especially permits, licences and bank loans.
10. get real about competition. collect as much information about competition as possible. have a broader view of what your competition is. a desi aakhada can also be your competition and a TT club also. it does not harm to have a broader view.
11. try and define your customer in as fine a detail as possible. his age, family and financial background, clothes he wears, education, ambitions, aspirations, fears, concerns etc. Why would he want to join a gym? why does he want to build body? this type of thinking and such questions will help a lot.
12. also, simultaneously start working on the contents of your website (you must have one). Design pages titled who we work with and how we work. you will observe that as you continue on these two projects, your ideas will undergo a lot of changes, they will get clarified. you may have to revise done parts of the business plan, but that will be good for you.
13. to make it real, you will have to get out, move around and collect information. this is not an armchair exercise.
so, get going. all the best to you. if you get really stuck somewhere, ask me.
your well wisher
r c kathale