I worked at a software company with a retired physical therapist.
He recommended a very simple exercise using a rubber band.
Wrap it around the fingers and push all five fingers with an outward movement.
I started with thin, pliable bands, gradually increasing resistance with stiffer ones.
My tennis elbow cleared up months later, but it never forced me to curtail activities.
Mine likely occurred from regular yardwork, like trimming or heaving garden tools.
He said the only other solution involved complete rest - and that ain't happenin' with me!