A. Elevated surface. Note - the higher up the surface = decrease in intensity. If you want to increase intensity take it to a surface closer to the ground. If you want to decrease the intensity take it to a higher surface (the highest surface being a wall)
B. If elevated push-ups become to easy, you can take it to a push-up on the ground. Just make sure you can still stay in a full plank position.
***If adding a push-up in this elevated position is still too much for you no worries. Hanging out and holding a solid high plank from any elevated surface is a great way to work on getting closer towards feeling comfortable doing push-ups (and builds great core strength)