That is normal and a good thing. Trust your instincts for self preservation. Only when you have built skills one by one and know you can walk out a thirty foot limb to lighten the end is it a possibility that you can do it reliably, repeatably, and safely."The thing that I struggled with the most was limb walking because I just didn't trust my gear. The instructors told me that feeling this was normal and all psychological and that I would get better at this."
Ignore any ego or someones comments that you should be able to do a thing.