Most people start out meditating with one goal ; to clear the mind and escape from the world. It takes a lot of time and experience to realise that even an agitated meditation, when the mind simply can't shift all the to-do lists and self recriminations, is actually the main point. In meditation we train the mind to control rather than defeat this agitation, so that we may live in peace with it. This doesn't mean that you won't be calmed by the peace of turning down the volume on the mind-chatter, but by learning to manage that part of you, a certain harmony will come into play.
Think about how much time you spend battling with yourself - I am going to be better at this, or that will get better when I am over the other ; life is a constant list of hurdles to leap, and it is exhausting thinking of ways to jump higher and further - especially when all there will ever be are more obstacles ahead. So meditation and mindfulness allow us to switch off the battle, surrender and play dead, then save our energy to actually fight the real fights, rather than the countless imaginary ones, worrying about the next blockage. Guess what? You'll be much better able to cope with whatever stands in your way.