"Half the fun of SUP surfing is learning. Get out for a session every two days and you will feel a 6 pack coming on - it really does work your core muscles.
Once you learn the basics of SUP surfing taking it to the next level so you can maximize your surf sessions is done by practicing certain things and just paddling on the flat days consistently.
Here's a few things to do on flat days that are both fun and great training...
Paddles both sides with feet offset. Then switch natural to goofy and do the same.
Practice turning by reverse paddling on one side and then finishing the turn on the other. Do 360's - both sides
'Stall turn' by stepping back to the tail and paddling to turn - practice 360's - both sides.
Throw in some sprints to simulate taking off on waves. Start with short rapid strokes.
Paddle! Paddle! Paddle!!! Take the scenic route - nothing beats just paddling around.... "
Have a look on a map, find a cove out of the wind, or a river or a lake and get out there Oliver before your gills dry out!

And Revvin, thanks for that Laird at Puerto link, I am amazed at how skillfull he is.