I'm actual a BCG consultant in the ME and also PTO champion for a few cases now so will share my experience.
To be honest with WFH can be extremely dificil to do anything but work.
Me, as a PTO champion (btw, PTO doesnt mean personal time off at bcg lol), implemented several initiatives to ensure health lifestyle:
1. every day we have 1 hour of protected time (you can do whatever you want during this time)
2. every week we have one evening protected (after 930pm we are supposed to stop working)
Also, as part of the PTO role you work on your working norms (maybe I'm a morning person versus a night person; 1 have a few commitments i want to protected, etc)
Now, working at MBB in ME is definitely quite intense (i work 75h+ a week, usually around 90h depending on the case) therefore having time for exercise, going out etc i leave it more for the weekend.
Hopefully this helps (and doesnt scare you away from applying ahah)