The fastest, easiest way to be zen is to be it right now. Just do it right this second. Like, right now.
If you keep missing the chance to be zen, you can do it right now. Or now.
If you've missed all of these chances, now, past and future, then there are some other ways to be zen, and they're not that hard or confusing. Last chance...be zen NOW!
OK if you missed that last chance, don't fret, though you are zen right now (and now) and you don't realize it here are other ways to be zen while realizing it and also not realizing it simultaneously:
1. When you do something, don't do something. We are always doing something, whether it's an activity like tennis or a non-activity like tennis. The key to being zen is to do nothing while you're doing something. So the next time you're doing something, stop doing it, and also do it.
2. Stack rocks on top of each other. No one knows why but when you stack smooth rocks on top of each other, you are zen. Once you get them stacked you have to protect them with your life though to make sure they don't get knocked over by some asshole. If the rocks get knocked over, you're not zen anymore.
3. Live your life sitting in one place. This means you'll need a bed pan, you'll need a nurse, you'll need a chef, you'll need to work remotely. You have to remain sitting or you lose the concentration of zen. In fact there is no concentration needed to be zen, but you'll need to concentrate while you're not concentrating. But for God's sake, don't be a disgusting asshole and try to concentrate.