Thoughts on turning 40

I turned 40 about 10 days ago. A friend told me, "the weeks leading to your 40th birthday are the longest years of your life." I didn't think 40 was going to bother me and it didn't until about a week before my birthday when I suddenly got really stressed about it. We celebrated with friends the night before and that morning and had a great time and the day passed. Once the day was over suddenly it didn't matter anymore that I had turned 40. It didn't change how I felt, it didn't change how I looked, it didn't change how anyone treated me. It was a complete and total non-event. I'm still not sure why it bothered me so much. On to the next 40.