WTF? What's wrong with carrying a bag ? Unless you are very old and frail, surely, the average golfer could lose a bit of weight by carrying their bag.

 Just wait until you have your first attack of lumbago. Just wait ...

It's got damn all to do with fitness. I agree that anyone healthy should pull or push a trolley (no excuse if you're fit for having a motorised trolley, and none at all for a buggy). But for a lot of people, carrying a heavy bag, even with decent quality straps, is asking for back problems. [Cue someone saying 'I only get back problems when using a trolley, but I don't when carrying a bag'. Good for them. It's a case of the exception proving the rule].

Back on topic - have hedgehogs fitted to my trolley and they work a treat.

The reason you will get a bad back from using a trolley, is when you are pulling it, you are twisting your spine.  Always push a trolley in front of you. (my surgeons recommendation)

I read somewhere that carrying a bag will do more damage to the course than a trolley will, due to the spread of the weight.

 I read somewhere that carrying a bag will do more damage to the course than a trolley will, due to the spread of the weight.

Yep - that course has a "fatty" ban if 3 days of rain falls!!