It scared me to death to think about improv, but I got hired for a year at Second City in Chicago, which made me nervous, but I found I could improvise. Then I was in a group called the Ace Trucking Company, which we'd do, like, a half hour set of material, then open up for improvisation.
Most things I get hired on, I get hired because I improvise something funny, or they just think I look weird.
Only having one melody instrument in play at a time meant that we could improvise more in our practices.
I went to theater school, and if I spent time with one school of thought in this whole acting game, it's the Meisner approach of improvise-based acting. This does not mean that you improvise your acting, but that you focus on the other person.
I like to improvise.