dynamically passing header authorization value for Request

Hello,

Here is what I need help to find solution:

1. There is one endpoint which will will generate the Token in the response. 
2. Now this response is going to be used as a "Header" in another request. 

The token gets expire in one hour and for me to keep my test alive and automatic, I am seeking to some how retrieve the token from first endpoint/testcase and then dynamically pass it to the other test's request header. But I don't see an option to take value from groovy or data source etc.

I saw one post where creating event handler is suggested but I am not sure how can the event handler take token value from a test case response. 

Appreciate any help.

Thanks

Basant