I prefer to push myself further when I am on the fence about facing a challenge. I am the person who would rather take risks to pursue a result
than just stay in place to guess the result. For example, I often motivate
myself when I hesitate ahead of an extreme challenge like a roller coaster ride. I would
say to myself, "It's short! Just do it!" Because I know I will enjoy
the excitement (that comes) just after the fear. I will also choose to have a try when I receive
some challenging projects at work, even though my heart is saying to myself, "give up." Because I know I like the feeling of fulfillment (that comes) after success. So calmly
thinking always motivates me, I will compare the pros and cons in my mind and
make decisions after that.
"I'm on the fence"/ "I'm sitting on the fence" : this is normally used when you are undecided about something, usually between two options (a fence separates two areas). Hence "Sitting on the fence in terms of personality" does not work well here IMO.