It's good. One small point:
"At night" usually implies that he does it every night. But the second sentence suggests that this is a particular night.
- If he's just going for a walk on one particular night, the first sentence should begin with something like One night or That night.
- If he goes for a walk every night, the second sentence should begin with something like That night or Tonight. And if you want to be as picky as I am, you could change a walk to walks.

English Teacher