Living peacefully with rightious happiness itself is a great contribution / Service to humanity . A person not indulged in giving trouble to other creatures for his food - great service Not judging others rather be compassionate - great service Engaging into Spiritual book reading or clean & green activity in free time rather idle living or watching violence hours together - great service ..... this list goes on. To conclude be happy in your own circumstances without creating pollution at mental and physical level .that itself a great service to humanity .