|Congratulations for hitting the wall again!
You shouldn't be discouraged by you muscled not holding up (yet). You put quite a lot of strain on your thighs when pushing. And you can't really train your muscles by anything else in the right way. It helps to do street skating and other sports, of course, but each activity requires some special muscles. So be patient and persistent and try to skate a ramp several times a week and you soon will notice the improvement.