Thank you Katy, but I still don't understand the structure. Does " while" in this sentence mean " until" or something? why does " sad" come behind "while" instead of " sadness"?

Hi, it might help you to replace the word “journey” with “experience”. They are saying that when they experienced grief, although it was very sad, it was also a healthy experience for them, because grieving is a healthy process to go through. I hope that helps, let me know if not.