It doesn't have to be complicated. In fact, the simpler, the better.
Right now. Stop everything.
Sit with both feet flat on the floor.
Rest your hands, palms down, on your legs.
When you close your eyes, focus all of your attention on the sensation of the hands resting on the legs, feeling the warmth, the touch. Return to this sensation every time your mind wanders away.
Then focus on the air flowing in and out of your nose, or the movement of the ribcage with each breath.
Just this moment. Just these simple sensations. That's all that matters right now. Everything else can wait.