How does the Giver feel after he transmits the first memory?

The sequence in which the Giver gives Jonas the first memory begins in chapter 10 and continues into chapter 11.  Jonas is asking why being the Receiver of Memory is so important.  Jonas believes that he is only going to be listening to memories that the Giver has about himself.  The Giver patiently explains that Jonas will be receiving many more memories than that:

He leaned back, resting his head against the back of the upholstered chair. "It's the memories of the whole world," he said with a sigh. "Before you, before me, before the previous Receiver, and generations before him."

Jonas is shocked to hear about the enormity of memory that the Giver holds, and Jonas hears that the memories are difficult for the Giver to endure:  

He rested for a moment, breathing deeply.  "I am so weighted with them," he said. 

The Giver tries to explain further by using an analogy about sledding downhill in snow, and Jonas is completely lost.  He has no idea what the Giver is talking about, so the Giver decides that Jonas's first memory will be a memory of snow and sledding downhill.  
Jonas loves the memory and is exhilarated by it, but the Giver is exhausted by the process.  Giving the memory to Jonas is work; however, he also feels "lightened."  The act of sharing the memory may have been work, but it also felt good.  It is a relief to be able to share that memory with another person:

"That's right. A little weight off this old body."