Whether he would pay Service tax or would liable to pay under "profit & gains from business and profession". One is indirect tax while another is come under direct tax.
1. PGBT under Income Tax is applicable in your case. You can follow provisions under 44AD or normal tax provisions Under Income Tax
2. Yes there is a service provision involved as you are charging fees for using your gym equipments in your gym and providing health instructions. But ST will be applicable only if such service exceeds 10L in the present year. Moreover VAT will be applicable only if you are selling your gym equipments. that too turnover criteria for such sale must be more than 10 Lakhs