I dont think the youth leader is saying skiing is bad because it is fun, or that skiing is bad. He is saying (basically) to have fun, but remember remember your relationship with God. Do not let a activity make you lose your love for God.
As far as heaven, I think if you asked any youth leader or minister/preacher/pastor "If I believe Jesus died for our sins, and repent and truely feel sorry for my sins and ask for forgiveness from God, but can't help myself and sin, commit adultery (and truely in my heart want to stop, and ask God to help me), will I go to hell ?". I think he will say acts dont get you into heaven, love for God and Jesus will.
If you become addicted to Coke, your life is going to suck. Your youth leader is basically trying to help your life not suck, doesnt have anything to do with the afterlife. For those that dont believe, as a believer I think it is not acts that God wants, it is a relationship with him and Jesus. I think most Christians would not want to condemn you, but just pray that you get a relationship with God and Jesus.
If you are a non Believer, how about every night pray to God and say "God, I do not feel your love, please let me feel your love". I am not asking you to not do any particuliar act, not asking you to not have sex, drink, etc, just pray to God and ask for him to enter your life.
I believe when the Bible says "do not take the Lord's name in vein", it does not mean dont say Go* Dam*, it means do not things to other people in his name. That bible verse would condemn the crusades. If a Christian parent's 3 year old son says Go* Dam* and the parent whips his butt till it is red and blistered, the parent, imo is the one taking God's name in Vein.