Well fear can be a good thing but when we feed into it too much and choose to stay comfortable instead of taking a leap of faith it can get in the way of our quality of life.
I think imagination is am amazing tool I use it to visualize my life but just like thoughts we need to keep out imagination in check by focusing on the things that make us feel good and inspire us not the things that we don't want to see happen!
So use that imagination its a great tool to dream up the life you desire :)