BIW will chew you up and spit you out unless you apprentice for the right trade. If there aren't apprentice opportunities for pipefitters, operators, sprinkler fitters, milllwrights, boilermakers don't do it. If you get stuck doing a job like painting, laborer it's hard to move and it will fuck you up. Every job is hard and physical but they aren't going to wear you out if they are investing in you long term, plus you can take those hours and apply them somewhere else or to a different trade if (when) you decide.