It's true what they say consistency really is key, but I agree it's so hard. For healthy eating I find the ONLY thing that really works for me is keeping track of everything I eat in an app. That way not only am I mindful of calories, but also sugar/sodium/fat/etc. The app I use let's me know...
I agree that calendars are helpful. For important dates that I need to remember a gift or card for I add in an additional calendar reminder the week before so I have time to prepare.