There really are no off days when it comes to your health, or your exercise regimen.
You’re training even when you’re not lifting.
To look at the non-lifting days as ‘do nothing’ days is wrong.
Flexibility & mobility are critical to your strength and performance. You should be working those aspects all the time.
Rest & recovery – both mental and physical – are also critical. If you want to perform at an elite level, you must recover just as hard as you train.
So, even when you actually have a planned (or unplanned – listen to your body sometimes) day of doing nothing, make sure you do it well.
By that I mean: invest in lowering your stress levels on these days. Do something for yourself. Get a massage. Meditate. Go fishing. Do whatever it is that truly relaxes you.
If you never make time to truly relax, you’ll never reach your opposite peak either.