How much ever unfit one is, just showing up for a long period of time changes oneself. All one has to do drag oneself to the class, day in and day out, and then universe takes over..
I've been doing strength training once a week since the pandemic startet, and it has been great. Obviously I could have made much more progress with more frequent training, but I still look much better naked and more importantly, I feel much better. So many random aches and pains have just disappeared.
This works amazingly well with a home weightlifting gym. Even 15 minutes before a meeting on a busy day can be gold.
This is without much immersion (due to lockdown then traveling), and the instruction is online, and I've been a lazy bum about additional study.
It's made me pretty optimistic about learning new languages in general, and I'm 50 so the brain isn't exactly a sponge anymore. More like a sieve.
The best thing is that even if some weeks or even months I do not feel like studying at all, I can just continue with the Anki decks for 5-10 minutes a day to make sure I continue to retain what I had already learned. It has not become my bedtime routine/habit.