I genuinely believe that an emptier space is a happier space, that the energy flows more freely around a decluttered room and that it becomes infinitely easier to relax both mentally and physically in such a place.
I also suspect that many people have a lot of things they don't necessarily want, or need - things that have been acquired and then kept through habit. The chances are probably also good that the things you never look at, use or admire are things that someone else would give their left arm to own, that they could never dream of affording or just don't know how to get any more.
So follow this 2-part plan to achieve an inner glow that will last you for weeks.
1 - Declutter. Go through your things, one by one (this is very important, look at each item individually) and think 'do I really need this? Do I? Really? Why?'. This way of looking at things has helped me get rid of stuff that I thought was a life fixture. Turns out I didn't need it or especially want it at all. I was just used to it.
2 - Give your ex-clutter to someone else who really wants it. Advertise it on your local freecycle group. Take it all to a charity shop. Give it to your friend who has always really wanted it.
Declutter and share - you get happy, and you will make someone else just Glow with happiness as their dreams unexpectedly come true. And it's green too, reuse and recycle!
Here is a great link suggesting places you can share your old things out to (other than the nice easy option of the local charity shop you support):
http://www.thedailygreen.com/living-green/blogs/save-money/declutter-donate-stuff-460210
I can't promise how many places have an equivalent in the UK but I suspect they are definitely out there, all it takes is a quick google search.
Here's a good example of this idea in practice:
http://www.dosomethinggoodday.com/modules.php?name=News&file=article&sid=23
Good Luck :-)
(and here's something funny, just for smiles) :-)