I started meditating a couple weeks ago, and I've been finding that I seem to be incapable of relaxing completely. There's always a tension in my back and shoulders that I can't seem to ease. I've tried stretching, ignoring it... is this normal? I used to meditate when I was younger, and I don't remember having any such problem. (I'm 28 now, as opposed to 16.)
Tension in back and shoulders lends itself to talking about doing yoga postures before meditating, or some other specific stretches. You could also do the Energization Exercises before meditation.
But these are things that would require some research on your part, or a 5-page letter on my part, so I am going to make a suggestion that has helped many people in a very quick and simple way.
If you are meditating on a chair, lay a folded blanket across your lap and rest your hands, palms up, on the blanket such that your hands are at the junction of leg and torso. Lifting the height of your hands often releases pressure in the back in an almost magical way.
If you are meditating on a kneeling bench, you can do something similar.
If you are meditating cross-legged on the floor, you can lift your hands in a similar way, but the floor sitting position may be part of the problem. Make sure you have adequate height supporting your hips – in other words, be sitting on a pillow to help tilt your pelvis forward and make it easier to sit up straight without strain.
If you normally sit on the floor, you might try sitting on a chair with something across the lap, and see if the pain goes away. Another help on a chair can be to put the edge of a pillow or blanket under your tailbone to give you a slight tilt forward.
You can also take a look at How to Sit Comfortably in Meditation to see a visual representation of all the above tips to sit properly for meditation. I hope one or more of these simple tips can solve your problem. Otherwise, you might do well to practice more yoga.
Joy to you,