If you have read any other of my articles, you'll notice that I am a big believer in the mental aspect of guitar playing and practice.
Mental techniques have played a massive part in lots of other areas of skill, but instruments, and guitar in particular has been overlooked.
Even a little awareness of how we use our brains when practising guitar can make a big difference to our playing and also enhance the feeling that we get from using practise time constructively.
How many times have you sat down to practise and ended up going over the same old scales, or chord progressions? Only to put down your guitar and feel that you haven't improved even slightly, or even that you are wasting your time and that you'll never be able to manage that new chord or melody without finger surgery. Perhaps you've thought that you'd take up a more acheivable pastime like embroidery or something.
If we can change our thoughts about what we are doing, are aims and reactions, then our playing, practise and life in general will seem easier and will run more smoothly.

The next time you sit down with your guitar, make a conscious effort to really concentrate on your playing. What your fingers need to do, how your hands need to feel, how other parts of your body are feeling, what your fretting hand needs to do to move to the next change, how your strumming or picking hand needs to move. Every single thing that you can be aware of when playing, consciously become aware of.
I know this might sound a bit strange if you are someone that has never tried this kind of thing before. Believe me though, this does make a difference in the long run.
When you first start to notice these things, you may think that your playing is worse than before you started noticing.
It isn't, you are just more aware, and awareness is the first step on the road to improvement.