Pitfalls of cross training

I love the way cross training helps me take some of the stress of certain parts of my body! But I was a little unprepared for the way it can bring on new stresses to other parts ( head ). I am so used to what kind of a runner I am that it was hard to try something new and not be at the same level. It takes a while to be just as good at swimming or biking as I already was at running, and I'm not used to being a beginner at anything for very long. Just learning how to swim or bike doesn't make you good at it right away, and the fitness level does take time to build up.

Also, getting chased up a hill by a dog when you are at the end of your ride is a little off putting to say the least. I know exactly how to handle those situations when I'm running, but I'm not sure what to do yet while I'm biking. Falling is a major fear for me....