A while ago a friend told me she has difficulty meditating because she finds herself feeling all manner of twinges, aches and unusual sensations that she can't seem to switch off and tends to become fixated on. Like so many people who pick up some basic information on meditation, her sincerely held belief was that she was supposed to block out any bodily sensations and that, in failing to do this, she'd failed to meditate successfully. People often suspect that if they get the posture and breathing exercises correct and put them into practice, the peaceful stillness they've read about should just come. It can be a shock when aches and pains seem to arise when in a meditative state, rather than disappear.
The main reason for this is that all the little processes your body is going through and the issues it's having are blocked out by your non-stop schedule. Meditation doesn't invite pain. Rather, it brings it to the forefront of your mind to be addressed. After working on breathing and posture the next thing I do in meditation is expand my field of awareness to include all the energies and sensations in my body. (This is necessary for astral projection too. I think that in order to transcend the physical and 'escape' it in some way, it's obvious that you first need to address and communicate with it.) When you feel tension, tingling, itching or aching in certain areas, try slowly naming it in your mind first of all. With an itch, for example, rather than just breaking the meditative state to scratch it, try leaving it and instead acknowledging, 'itching itching itching' in your mind. It's probably years since you've given an itching sensation a chance to play out rather than simply scratching it absently. This exercise is a great practical reminder that each feeling and physical state is temporal. Letting the sensations occur and focusing on them instead of acting on them, it's not difficult to recognise how quickly they pass and become distant memories as the meditative state becomes deeper.
It's important not to intellectualise the pain. Wondering 'what could that be?', 'why am I feeling that?' is a break with a state of intentional acceptance. The ideal scenario is that meditation becomes a way of addressing pain in exactly the same way as we address pleasure - as something to reflect upon, accept and transcend. Life isn't actually meant to be devoid of pain. So, it doesn't make much sense to attempt to avoid it in the meditative state and subsequently distract or frustrate ourselves when we can't.
Letting unpleasant physical sensations occur during meditation is not only a relinquishing of the security of control but also a perfect reminder that you're not really in control of your body in the first place. Breathing is taking place on its own, without our permission or help. The heart is beating and the liver and kidneys are doing their job. Let the exercise encompass anything that distracts you during meditation. The sound of a door slamming, music from another room or a car in the street - these things can be included into the meditative state and processed as part of the experience. Acknowledge that you're hearing something by stating in your mind, 'hearing hearing hearing' and let the sound become part of your state of being.
Don't get me wrong. I'm no expert at this. I mean, the ideal is to be able to meditate with a fly buzzing around me and not even flinch if it lands on my nose, but come on, that's pretty tough to achieve! And I've been meditating semi-regularly for eight years! But what I do know is that meditation became much easier when I realised that striving for the 'perfect' conditions is actually detrimental to my own improvement.