I know a couple who does something they've never done before once a year - on their anniversary. And while I like the idea of doing something for the first time, their tradition begs the question:
Only once a year?! WTF!
So what I suggest is that you do something new, something you've never done before, once a week. This way you'll 52-tuple (fiftydouble?) your first-time experiences with respect to that couple.
And what could be a better day for this than Monday?
So every Monday, do something you've never done before. You cain either wait until Monday to come up with the thing, or plan ahead - it doesn't matter. Force yourself to come up with something new. It doesn't have to be anything of grandeur or even anything crazy, as long as you've never done it before.
Plug a chicken. Make an amigurumi. Solve a crossword. Fold an origami frog. Run 10 miles in one go. Go to the airport and pick a destination at random. Ask a stranger for their number. Order something from Starbucks you haven't tried before. Go bungee jumping. Stay up all night watching Game of Thrones. Work 24 hours straight.
This not only gives you exciting new abilities and memories (and in the best case, a photo collection full of interesting and fun pictures!), but also trains your brain into being ready. You also get to dig deep into your mind to find things you haven't done, especially after a while. But don't worry, your brain will adapt with time. The more you try to come up with new things, the more primed your brain will be to come up with them. Handy, isn't it?
Happy Madness Monday!