As you sip on your on your Big Gulp wondering how to get fit and wanting to lift weights here's an eye-deer. Bag-in-box! The kind that held the syrup for that empty calorie frosty beverage you got there in your hand. The bags are thick, strong and fairly easy to fill with sand, change weight, and best of all.... you can get them for free. If you don't mind getting some strange looks asking for them. They come in two sizes: big ones hold coke, sprite, dr.pepper; and the smaller ones hold nestle tea, power aid. I've got the smaller one here and could easily hold 30 pounds of coarse sand. And don't forget to get the lid to these guys.

What you will need:
Bag from bag in box syrup
utility knife
drill and drill bit
needle nose pliers
scale (if you're looking for a specific weight or you can go "eh, that feels heavy enough")
cups and funnels helps too

First I give it a little wash to get some of the syrup off, then I go to town drilling holes around the inside of the screw top.

Step 1: Treat It Like a Turkey.

By that, I mean take out the guts so you can stuff it with something better.
There are four things that's in there that I ripped out.
Little plastic thing that was drilled.
Little plastic thing with slits in it.
Little plastic thing that is pointy.
Finally long plastic thing that if you grab with pliers and twist and pull, it should come out. Careful if the the syrup is still wet like water.

Step 2: Helpful Tip

I got an orange juice bottle and drilled a 1 inch hole and just screwed it onto the threads. But double check to make sure that's the hole size you need. I'm not sure if all bag in boxes are the same.
Then I fill the oj bottle with 5 pounds of sand, then let it flow. Its a lot of transferring that I do, but it works for me.

Step 3: Helpful Tip

I got an orange juice bottle and drilled a 1 inch hole and just screwed it onto the threads. But double check to make sure that's the hole size you need. I'm not sure if all bag in boxes are the same.
Then I fill the OJ bottle with 5 pounds of sand, then let it flow. Its a lot of transferring that I do, but it works for me.
Also after I wash it, it usually takes a couple of days for it to dry. If I stick in the sun I'm sure it would dry faster.