Membership Fees. But before you learn how to find Lifetime Fitness deals online, you’d naturally ask yourself—how much would a Lifetime Fitness membership cost you? The prices of Life Time Fitness membership would vary depending on the location, but on the average, a single membership would cost you around $80 to $90 a month. Meanwhile, the initiation or joining fee is in the $200 range. Simply put, Life Time Fitness membership is not cheap by any means.