World War 1 changed the lives of Indians in the following ways.
1. The British had promised self governance to India after the war in return for the assistance that India provided in the war. After the war, the British went back of their promise. This led to disillusionment among Indians, including Mahatma Gandhi, who lost all trust in the British and intensified the campaign for freedom.
2. During the war, thousands of Indian soldiers had fought heroically along with the British on equal terms. Seeing the war effort of the Indian soldiers inspired the people of India and made them realize that they were equal to the British in bravery and heroism. This made them feel more deserving of freedom.
3. The continuation of draconian war time laws even after the war led to atrocities like the Jalianwala Bagh massacre and intensified the freedom movement in India.