Nothing will crucify you faster than your own thoughts. Better to not think at all, if you can do it. And if you can’t, if you must think, think about pure simple things.
Think about washing the dishes or doing the laundry. Think about things that must be done. And then let the mind be free of thought.
Everything you believe about the nature of your existence keeps you limited to the past. If you want to experience the moment unconditionally, give up all concepts of it. Just be present in your life as it unfolds.