[jdrols]

Squats and deadlifts.

You are forced to adopt good posture if you want to do them properly and with any heavy weight. You'll carry that posture with you into your daily activities.

[mod]

I can second this. Was doing 5x5 about a year ago, posture was drastically improved. People noticed.

Have since quit, posture has regressed.

Time to get back in there!