18? No way, go live your life. Have fun, get in trouble, experience things. LIVE. Don't spend the rest of your life in one building. Screw that! Money, pensions, and a 401k at 18, come on. I didn't get here until my 30s, I wouldn't give up one life experience for one more dollar in my 401k. When I'm on my death bed, I'm not going to be thinking, "Man, I wish I spend some of the money Ive been saving." Get the friend*k out of here, some of you guys are crazy.
My advice if you are considering working at UPS. Work for a few months, then join the military branch of your choice for 4 years active. UPS will hold your job like you never left. After a ton of life experiences (some good, some bad) with the military and about an age of 23-24 you can come back to UPS with all your seniority. Then you can be ready to work till you die. I personally think this is the best route for any young person. Go drive a tank, or be a grunt and kill someone for your country. That's living!