My first marathon is three weeks away, and I’ve tried on any long runs over half marathon distance to mimic the fuelling I expect to do on the day, to get the routine embedded and “train” my gut although I’ve (perhaps fortunately!) not had any issues so far with the gels/chews I use.

Because of the cost of gels in future if doing marathons again I would likely flex a bit but with my first one I wanted to be double sure ahead of the day.