I don't/can't rely on a mental calendar. I'll blame it on age.

I've been using Calendar Creator Software for years. I enter important birthdays, anniversary's, appointments, etc. in the program. I make an 8 1/2 by 11 one month on each page version which I keep on my desk. It has a 1" square for entering data. A 5 1/2 x 8 1/2 booklet form goes in my purse.

I get lots of calendars in the mail and I put the one with cats or animals on my office wall.