Because you are feeding it with warmer and happier feelings.

[What she says makes perfect sense to him. The shard is a tie to your world, but it is also a reflection of your view of the world. If that view is darkened by negative emotions, then the shard will reflect that. If they are warm and protective, the shard will also reflect that.]

I am so happy for you. Good job. I bet you will find things easier from now on.

[Or at least as easy as working with a shard can be.]