Rest days lead to gains
It's tempting to start your training journey and think, I'm going to train EVERY DAY. Workouts lead to gains, so the more you train, the more you grow, right?
Not exactly. Training breaks down your body, then rest days allow you to grow, adapting to the training you did. So while yes, training is required to create adaptation, rest days are what give you the gains.
Instead of thinking of rest days as days off, think of rest days as growth days, where you build muscle and allow your body to recover.
Workouts break you down. Rest builds you up.
The purpose of training is to create adaptation by breaking down your body. From building strength and muscle, to increasing endurance and flexibility, training at higher intensities break us down in pursuit of these traits.
Rest days are where you withdraw that hard-earned imaginary cash.
With the right stimulus, recovery is what takes you past your limits.
You're not missing out on gains
One of the difficult conversations I have with a hard workers is to convince that person to take an extra rest day. I usually ask, "Instead of working out 6 days a week, how about training 4 days a week instead?"
I'm usually met with hesitation because it's common to think that less training days = less gains. It makes sense! So instead, I frame it as taking an extra day to grow, instead of an extra day "not training."
As long as your training stimulus is appropriately dosed, more rest days might mean higher-quality training days, which can lead to better overall gains.
Training and rest are both important for growth, but framing rest days as growth days can help you find balance between the two.