Never tire of doing something
Definition 1 of 2
Pro Tip 1/3Extended Period
Use this phrase when something continues to interest you for a very long time. 
Even after years as a chef, I never tire of experimenting with new recipes.
Pro Tip 2/3Genuine Interest
It implies a deep, authentic enjoyment, not just a casual interest. 
She never tires of learning languages; she's already fluent in five!
Pro Tip 3/3Positive Emotion
The phrase conveys a feeling of joy or contentment in an activity. 
He never tires of playing guitar, it's his true passion.