If there's a single word to purge from your vocabulary as you explore mindfulness, it's 'why'. Try replacing it with the word 'what'.
So, what do we mean by this? As you meditate you'll become more and more aware of your own mind and the various things you've told yourself about the world, your own identity and your own past. If you come across a belief like 'I shouldn't take risks, better to play it safe' your conditioned response may be to analyse by asking 'why' am I like this? If you do, you'll end up talking to yourself, thereby ending your meditation right there. This may lead to some insights about your own psychology and you might feel terribly clever, but you'll quickly notice that why leads to other whys in an endless loop (anyone who's met at 3 year old can attest to this).
Instead, try this. As the belief surfaces, immediately accept it. Accept it no matter what, even if you think it's something you 'shouldn't' accept because if you did it would make you a worse person. It won't. Accept it and once you have, ask yourself 'what' - what am I going to do in relation to this new insight? Decide who it is you want to be in relation to it (Do I want to be brave? Do I want to change this belief? Do you want to leave it as it is?) and last but not least, act out your decision. You'll soon see that it's easier than you think.
It can be difficult to practice mindfulness in the modern world, especially a city like London, because we're bombarded by the implicit belief that everything must be figured out and solved. 'Why' is the word for that mindset - and I'm by no means suggesting it's a bad way to go about things sometimes. Why is an essential question, in its place. It's very useful for observing what is sometimes called concensus reality - what we as perceivers agree is happening in the objective world around us. But it should stay in its place, in the world seemingly outside of our inner experience - it has no place in a mindfulness meditation practice.
If you want to find out more about how to master the skill of asking what, come to one of our mindfulness intensives. You can read about these 2 day London retreats on www.open-meditation.org/intensives. The next one is on the 18th and 19th of May in Finsbury Park, London. Not only will it help you relieve your stress and learn the discipline required to be balanced, it will also help you understand who you are, so that you can understand what you're next action is going to be.