What can I do on my rest days to increase my gains?

It has been a while since I have done strength training but I recently started doing the recommended routine on r/bodyweightfitness (I do not have access to a gym). My schedule looks like...

Sunday: Strength Training, HIIT sprints

Monday Rest

Tuesday: Strength training, HIIT sprints

Wednesday: Rest

Thursday: Rest

Friday: Strength training, HIIT sprints

Saturday: Rest

I was considering adding light cardio to my rest days but is there anything else I can do on the days I am not strength training to increase my gains?

Edit: I am doing sprints for HIIT