If someone is unsure whether their intention for an act of worship is sincere, they should take the following steps:

1. **Renew the Intention**: Pause and consciously reaffirm the intention to perform the act solely for the sake of Allah. The Prophet Muhammad (peace be upon him) said, *”Actions are judged by intentions”* (Bukhari, Muslim). This means the sincerity of an act is based on the individual’s internal purpose, so they can renew it whenever doubt arises.

2. **Seek Refuge from Shaytan**: Doubts about sincerity can sometimes be a whisper from Shaytan to discourage or confuse the person. Seek Allah’s protection by saying, *”A’udhu billahi min ash-shaytan ir-rajim”* (I seek refuge in Allah from the accursed devil).

3. **Focus on the Act, Not the Doubt**: Perform the act of worship as best as possible, focusing on fulfilling its requirements. Overanalyzing sincerity can lead to scrupulosity (waswasa), which may hinder worship.

4. **Ask Allah for Help**: Make du’a (supplication) asking Allah to grant sincerity. A beautiful du’a from the Sunnah is:

*”Allahumma inni a’udhu bika an ushrika bika wa ana a’lam, wa astaghfiruka lima la a’lam”*

*(O Allah, I seek refuge in You from associating anything with You knowingly, and I seek Your forgiveness for what I do unknowingly)*.

5. **Remember Allah’s Mercy**: Allah knows what is in the hearts and understands our struggles. Striving to be sincere is itself a form of worship and is rewarded by Allah.

6. **Practice Gradual Improvement**: Building sincerity is a journey. With consistent acts of worship and self-reflection, one can grow in awareness and purify their intentions over time.

Ultimately, focus on Allah’s pleasure and rely on His mercy, while striving to improve with humility and persistence.