Something I thought of yesterday evening (yes,I'm that sad, I think about the forum when I'm not on it), Dave, does your bike, which sounds like a mountain bike style, have knobbly tyres? If so, you can improve your percieved fitness no end by changing them to less knobbly ones (unless you are intending to do serious off road riding). Knobbles cling to tarmac and act like glue. Slicker tyres, pumped up well, will improve your rolling resistance, and it'll feel easier...