Job & Pregnancy?

Okay so I'm not pregnant yet but my SO has started pushing for us to put 110% into trying so I want to know before it happens. I work in a physically demanding job position. I work in below 41 degrees all day for 9 hour shifts and am constantly lifting weights between 25-100 pounds by myself... When should I stop lifting so much weight after conceiving? Can the cold temperatures hurt the baby? If so when should I stop being in the colder temperature?