Start 2018 Off Right — With the Perfect Gym Membership For You

Gym: Orangetheory Fitness

Cost: Expect to pay $6 to $28 per session; there are no long-term contracts or enrollment fees.

Amenities: This is an intense, heart-rate-based interval-training experience, with nationally certified coaches to give members options and ensure they don't over- or undertrain. There are bikes or striders for those with orthopedic issues, and ability levels include Power Walkers, Joggers, and Runners.

Who it's best for: People who want results but don't want commitment.