Handlebars dont wait for Ember Ajax

My Problem is that the handlebars is not wating for the ajax request to be finished.

My console is like this:

1. It starts with "starting" from the function in the controller.
2. Then the {{log workouts}} in the template which is undefined because the ajax is yet not ready.
3. And at the end the data from the request.

So this is a part of my code of my workouts controller

workouts: function() {
        console.log("starting");

        this.get('session').authorize('authorizer:custom', (headerName, headerValue) => {
            var obj = {};
            obj[headerName] = headerValue;

            Ember.$.ajax({
                type: "GET",
                url: this.requestEndpoint,
                headers: obj,
            }).success(function(data) {
                console.log("ajax: "+JSON.stringify(data));
                return data;
            }).error(function(error) {
                return error;
            });
        }); 
  }.property()

And the Handlebars Template is like this:

{{log workouts}}

How do I solve this? Maybe: Is there a way to transform this code into a promise? Or is there a "wait for ember" option?