When I feel fatigued I rest until I feel better. I don't let anyone tell me when i should get up. I listen to my body....it knows best.

Stay as pain free as possible and don’t refuse narcotics if needed. Pain will consume your energy, sap your optimism, and leave you feeling sad and helpless. I find that getting comfortable from a pain pill doesn’t make me sleepy- it gives me energy and hope

For me I find that fatigue is directly related to the amount of quality sleep I get the previous night. So I'm going to bed at the same time every day and an hour or two earlier than before and listen to gentle ,comforting music turned down low. Laying down quickly reduces my body stress. It gives my body a chance to relax before attempting to sleep.
I now sit when ever I get the chance and it helps.
And If I over do it , I find a safe place to just sit and nap on the spot. Waiting just intensifies the fatigue and lengthens recovery time for me.

I've read alot of the responses and knowing everyone with MM has different reactions to whatever meds they're taking, how long they've had MM, etc., this is mine. Diagnosed four years ago, I was on Velcade and Revlimid. I've worked every week, five days a week at Hobby Lobby closing shift( home at 10-10:30 p.m.) I've gone on vacations and just prepared myself that there might be a diarrhea issue, which there were. About a month and a half ago my oncologist took me off Velcade and Sam just taking my Revlimid. He said they couldn't find the M protein in my blood. Good news I guess. But I digressed, I have fatigue all the time, but never have I ever taken a nap in my life. I get about four or five hours of sleep at night. I'm up at about 9:00 a.m. and slowly start moving the body, bones are achy and I had foot surgery March 2021 and have neuropathy in my feet. Over all I'm in good shape for the shape I'm in.
I have an extremely positive attitude and for me that all I need right now. I live alone, no family around me and am 77 years young. I love country music and Nascar.
Hope you all have a good day and great weeks ahead.

I know this is more direct than one likes but my advice is move move move.