I definitely agree that just picking it up and start playing something you used to should get the feel back. I would make sure to warm up too with some exercises. The two things I usually do are spiders and a little rhythm with chord changes. These two will get your fretting fingers and strumming arm warmed up nicely.

Lisa McCormick's Videos on Spiders
https://www.guitartricks.com/tutorial.php?input=621
https://www.guitartricks.com/lesson.php?input=18583&s_id=1437

I do a slight variation starting at the low E string play each fret 1-4 on E then move down to A, play fret 1-4 and continue to each string until you reach fret 4 of high E. Then do them backwards. So in other words, play high E fret 4,3,2,1 then B string 4,3,2,1 until you get back up to Low E string 1. Then you continue by starting with low E string frets 2,3,4,5 ... A string frets 2,3,4,5.Your hand kind of looks like spider legs as you move down the strings and fretboard to the 12th fret. It's great to get your left hand loose. For a bonus do these using alternate picking (D,U,D,U...)

For the Rhythm Chord changes, it's just like it sounds. Pick at least two cords you know well or more if you want. Choose a simple strumming pattern like 4/4 and start strumming. Count each beat with a down strum of the cord, when you reach the fourth beat change chords "one,two,three,four (Change chord one,two,three,four change chord). Keep doing this until your timing and chord changes become automatic or until you feel warmed up. For a bonus either add some more chords or change the strumming pattern but stick with whichever pattern all the way through.

Then play that same old song you used to know...