The problem is that you’re happy. Writers need angst and struggle to inspire them, not happiness!
I’m kidding, but I know how you feel. You have to make it a habit. Just find time every day and write, whether it’s twnty minutes or two hours. If you can, make it the same time every day. After a while, you’ll be used to sitting down at the same time every day, and the writing will come and find you.
If you feel inspired at other times, by all means, write! But don’t let that excuse you from your scheduled time.