I have 3 years to kill, what should u do?

• mortgage life insurance
• work flow software
• negotiation skill

Ok so later in life i'm looking forward to becoming a cop but to become one you need your full licence so that would mean ill be around 21 before i could join the academy. I'm 16 now in year 11, so when i finish year 12 ill be 17-18ish so what should i do for those 3 years until i get my full licence. I was thinking of either getting a trade under my belt or just relaxing and living life lol. If i were to get a trade what is a good trade to have that is good to back onto if becoming a cop fails? And what is a good trade to have that will still be utalized even if im not working as it?

I have 3 years to kill, what should u do?