Getting potential clients to book a "discovery session"

I have got a list of 4000 people yet I find it difficult to motivate them to make an appointment for a “discovery session”.

I offer free sessions called Unconditional Self-Love Activation Session for people who have done my Self-Love Activation Course ($23,50) and a Femininity Formula Enhancement Session for women who haven’t yet worked with me.

I also have a Life Re-Design Session.

Question: how can I entice potential clients to a session?