often times one does not feel remote viewing, but they can feel the effects of scrying. One can push thier mind towards the feeling to trace it just to see who or what is watcing them. Most likely, it is a spirit one can not see. If you do want to shield yourself, either learn to close yourself, or imagine the color of your aura and imagine it as a magical shield.
If you are unable to do that just yet, imagine a physical shield around you.