Strong Back

The things you bear are more important than the body that bears them. You gain the following benefits:
• Your Strength or Constitution score increases by 1.
• You count as if you were one size category larger for the purpose of determining your carrying capacity.
• You have advantage on Strength checks made to push, lift, or pull objects.
• You have advantage on Strength (Athletics) checks made to shove a creature.

From: Izirion's Enchiridion of the West Marches