Used when someone does something kind and expects nothing in return. She volunteered at the shelter for your benefit, not for recognition.
Pro Tip 2/3
Personal Improvement
Implies a specific action was taken to enhance or help someone's situation or ability. The training was provided for your benefit, to improve your skills.
Pro Tip 3/3
Not Always Obvious
The person being helped might not always recognize or acknowledge the benefit immediately. The new rules were implemented mainly for the workers' benefit, even if they are grumbling now.