How can one get rid of the intense fear of showing off (riyaa') that prevents performing acts of worship in front of others and affects devotion (khushu') in prayer, and what are the ways to achieve sincerity (ikhlas) in deeds?

Fear of ostentation is a good thing, but one must beware lest it lead to inaction and prevent one from obeying, for this is a whisper from Satan. Therefore, one must be keen on sincerity and not abandon any act of obedience out of fear of ostentation.