Sexting shouldn't be only for those who are natural writers. If text + sex is an awkward combo for you, go slow and start easy with a shared memory.
Newbies often find this easier to start with because it doesn't require a trained imagination or any fanciful fantasy scenarios.
Remember that time we did ____?
It was so hot when we went to ____ and then did ____.
I was thinking about that night we first did ____.
One of the hottest nights for me was when we did ____.