The insert box itself should not be too difficult to lift. It only weighs about 48 lbs and has handles to make it easy to move.
The mantel itself does weigh a lot more. We would suggest opening up the mantel box, and taking a couple of pieces into your home, one at a time, to make the weight much more manageable. The mantel can then be assembled in that room, and you will not be lifting anything that weighs any more than about 50 lbs.
If you can have a second person help you, that would be preferred, or hire a professional off of a site like Angie’s List (now Angi) if you do not have your local handyman. The weight should not be an issue when moving only a few pieces at a time as many of our customers do exactly this.