自愿 (zì yuàn): Of one's own free will (Verb) — Meaning & Stroke Order

I voluntarily participate in this activity.

He voluntarily helps his neighbor repair the bicycle.

I am not staying up late voluntarily; it's because the project deadline is imminent.

Many volunteers willingly sacrifice their weekend time to provide free services to the community.

The students voluntarily organized an environmental cleaning activity.

This agreement can only be signed based on the principle of complete voluntariness from both parties.