cardio is over rated - dont you miss those smokes man-would'nt you like one now- you should have one- go on- it wont kill you
seriously though- just like you would increase the weight you lift if you were going to get stronger- do that with whatever cardio exercise you do- just up the intensity a bit- then a bit more
i always felt it easier to work on cardio if i am motivated by a fight or something- training cardio for the sake of it can be boring-so if you can do something like your skating that involves skill and you get your work out you will find it easier.