I want to send my members a letter notify them of the increasing of their monthly gym membership
Fee, but I don't know how to start? Any recommendations?

Thank you for being a member of <insert club name. We have tried to hold the line on a rate increase as long as possible, but due to increased cost of operations, we are forced to raise our rates effective <insert date>.

We hope you will continue to enjoy the many advantages of membership in <insert club name>.

etc.