If you’re training for the Virgin Money London Marathon, then your body is slowly adjusting to the strain of all the hard - but brilliant - work you're putting in.
If you're used to sitting behind a desk, it can be quite a shock to the system to start running and preparing your body for the big race.
By now, you might be finding that your muscles and joints are just starting to creak a little.
But don’t worry. It's perfectly normal.