Have you considered volunteering at a local group home or youth shelter? With your experiences, you would be a superb role model for the kids. You could even teach basic fire safety/first aid on a volunteer basis. I worked with teens during my counselor years and got both a satisfied, changing lives, feeling, and an adrenaline high (always a drama with a teen, such hormones!)
Granted, this will not replace the rush you felt as a first responder, but it may give you the feeling of helping someone.