Hi Joseph,
Your post reminded me of when I first came to the Lord. I didn't know how to pray. I was afraid and hurting by the fact that I couldn't pray.
I didn't know if I was supposed to kneel, sit or stand. More importantly, I didn't know what I was supposed to say either.
I remember hearing something deep inside that simply said that I would "talk to me."
That day, I lay upon my bed and placed a pillow over my face. I simply spoke -- sometimes aloud and sometimes with my mind (and always with my heart) -- into my pillow. I spoke to the Lord as I would speak to a friend (albeit a Friend who created all that is).
Now, your request differs from what I experienced. However, I think that I learned that you can pray in any manner that you find helpful. You can kneel, lay down, stand up or even walk. As Todd said, you can write to the Lord in prayer.
In fact, I love to walk somewhere apart from people when I pray. The point is to speak with the Father while you're alone. Matthew 6:5-15 is such a useful passage!
So, I don't think that there is anything wrong with being physically or emotionally overwhelmed while you pray. If we're going to be overwhelmed, I can think of nothing (or no one) better.
However, I would also suggest finding a way to pray -- undistracted by anything -- in which you aren't prone to feeling so overwhelmed. This might include a different approach to how you pray (e.g., walking, sitting, writing, etc.). Obviously, you're not bound by any of them.
Here are a couple of songs to encourage you:
"Oh Lord, You're Beautiful" by Keith Green
(first time he sang it):
https://www.youtube.com/watch?v=tqEa1Uo9UZc
"Be Still" by Angie Lewis
https://www.youtube.com/watch?v=TkMpQkDnsu4