I would like to start a list of all activities you can do at M4 now to keep motivated, if you so wish:
Clear your loadout and backpack completely. Go to your bank and choose 4 legendary guns you have not used, choose a new shield, grenade mode and try and find a com that might work. Try the proving grounds then slaughter shaft, or whatever. Then join some friends or match-make. Get the feeling of challenge again…
Try to complete content you find too easy with purple, blue or white variety weapons.
With obscure kit try to complete proving grounds before 25min timer passes.
Start a spreadsheet and itemize your loadout. Use this to help speed up quality trades. Also get to know the RNG and what you don’t want. Spead up your databasing skills - a commercial skill. Google spreadsheets are free.
I hope people add more suggestions… Sensible and otherwise - I’m sure.