Steam it.
Steamed celery will retain flavor and almost all of its nutrients.

Eat in five to seven days. Eat fresh celery within five to seven days to
enjoy its maximum nutritional benefits.

Eat the leaves. Don’t discard the leaves — that’s where celery has the most calcium,
potassium, and vitamin C. But because they don’t store well, consume celery
leaves within a day or two of purchase.