There are a many ways to say "Happy Birthday" to someone special, but only one way that makes birthday wishes special: you need to personalize the birthday wishes you send to them.
All the birthday wishes here have that personal touch you need. The best way to show you what I mean is to show you a generic birthday wish and what I would do to personalize it.
Here's one: "As a husband, you’re wonderful. As my best friend, you’re simply amazing. Now that you’re 40, you’re, well, perfect. Happy birthday, sweetheart!"
There are three ways to personalize this birthday wish (without changing its overall message):
You change the word "wonderful" to any other adjective (e.g. inspiring, supportive, loving).
You can also change the word "amazing" to another adjective (whatever you think will make him feel truly special on his birthday).
Plus, you can change the word "sweetheart" to your own term of endearment (such as darling, honey, sweetie pie, a cute variation of his name or just his name).