Pretty good, just few things...

For the walk cycle:
- his feet are very stiff. Try acting it out, when you foot touches the ground during a step the weight goes from heel to toes:



- he seems to be leaning back a bit too much (his head is pretty big and that makes it seem like he's of balance). Lean his upper body forward.

The lifting:

The ease-out around fr 60-85 is completely unnecessary. Just animate the walk cycle straight into the 'looking at the box pose' and hold that for a sec or 2.

Have him go into the antic (fr 128) faster and change the pose: Have him antic up (stretch) and back and have his arms move up and back as well and his palms open (antic should always be opposite to the action you make). Here's an example of good antic:
Heavy_Lift.mov - YouTube
Yours doesn't have to be as strong, but you get the idea.


Have him move down to grab the box way faster - use sharp ease out.

Hold pose 138 for at least half a second, then antic down, then swing the box up faster (ease out).

on the top do overshoot and settle. Then move his legs a bit - that little side step that weigh lifters do after they lift the barbell - redistribute the weight.

Just look it up on youtube, there are some good examples
Weight lift animation - YouTube

it's different than yours but you can study the way it was done to show the weight.