I do find WFP harder work though - unlike many here. It may be because my arm muscles are still adapting.
Trust me, you're doing it wrong - look at the size of your thigh muscles (quadruceps) compared to the size of your arm muscles (bi + triceps) and figure out which will do the most work for the least effort.
Use the spring/bend of the pole, combined with a rocking motion between your front and back leg to do most of the work for you, whilst keeping the pole more or less stationery because your arms don't move.
If that doesn't make sense ask someone who's been wfp'ing for a while to show you or do a search for wfp videos
If it helps, we get a reduction on our EL + PL because we use wfp, but we'll never be 100%. Consider it as another string to your bow, not the be-all and end-all of window cleaning.
HTH