Short answer: the first six weeks decide it. People stay when they build a habit and feel part of something local, so the marketing that matters is the kind that keeps you visible to people who already joined.
Acquisition is not the problem, month two is. Most studios can fill a January intake. The revenue comes from the people still there in March.
Local belonging beats a discount. Members stay at the place that feels like their neighborhood gym: familiar faces, local events, a community they see elsewhere. Being visible in a local community hub reinforces that in a way a national ad cannot.
Give them a reason to come back this week. A challenge, a class, a member perk. Something specific and dated.
Partner with the businesses around you. The smoothie place, the physio, the running shop. Cross-offers between local businesses cost nothing and put you in front of exactly the right people.
Where the plans fit. Single studios usually start on Small Business. Multi-location gyms and studios move to Professional Services, or Corporate when there are several locations to feature across the 904. See current plan prices.
The retention lever people miss: a member deal aimed at your *existing* members, not new ones. A perk for staying is cheaper than a discount for joining, and it does not devalue your rate.