Make the following sentence more detailed by adding descriptive words and phrases.
The dog is running.
The agile, eager dog is sprinting joyfully, its long legs fluidly covering the green grass with incredible speed and agility.
Complete the following task based on the instruction and optional input provided.### Instruction:
Make the following sentence more detailed by adding descriptive words and phrases.

### Input:
The dog is running.

### Output:
The agile, eager dog is sprinting joyfully, its long legs fluidly covering the green grass with incredible speed and agility.