That's the trick! Try it out the next time you have a hard time keeping a new strumming pattern while singing! I have used this trick many, many times, and it has helped me to get that "Patting your head, rubbing your belly" feeling to go away.
The two most important things I schedule - the stuff I'm never supposed to move? ME TIME and SLEEP TIME.
You still have time. You’re not too old, you haven’t spent your final chance. I personally don't think you have to be sad to write a sad song though. It is true that in the hardest times of our lives we come up with some of the best stuff to write.