In view of the above-mentioned statement, you have to describe five ways/sources by which we can develop sincerity in our worship and actions.

Sincerity is the spirit of worship and actions. Allah Almighty accepts only those actions that are based on sincerity. One of the most important characteristics of the believers described by Allah Almighty in the Holy Qur'an is that their acts of worship and deeds are only for the pleasure of Allah Almighty. The Holy Quran States: 

وَ مَاۤ امُِرُوْۤا اِ الَّ لِیَعْبدُُوا هاللَّٰ مُخْلِصِیْنَ لَهُ ال دِیْنَ   (البینۃ5: 98)

Translation: And they have been commanded no more than this to worship, Allah, offering Him sincere devotion.

In view of the above-mentioned statement, you have to describe five ways/sources by which we can develop sincerity in our worship and actions. 

Answer: 

• Fear of Allah

            Fear of Allah is the most important means that enables man to increase his sincerity. A person who realizes the greatness of Allah, that there is no power except Him and that the one that created the universe out of nothing, that takes care of all living beings and shows mercy to them is Allah is affiliated to Allah with deep love. He understands that his real friend in the world and the hereafter is only Allah and hence the one whose consent is necessary to seek is only Him. Along with this strong love, he fears Allah.

            Fearing takes place when a person avoids the attitudes that Allah rendered haram and is not pleased with and when he fulfills His orders without any laziness. A sincere person who fears Allah knows what attitudes He will not be pleased with and steps into action to correct them. For instance, if his soul has a tendency and weakness toward worldly possessions, he notices it. In that case, he uses his wealth in the way of Allah in order to overcome that weakness. 

• A level of belief that can appreciate Allah

            One of the responsibilities of a believer is to attain a level of belief that can appreciate Allah as it is necessary by being aware of the fact. 

To be able to appreciate Allah can be attained by knowing Him with all of His names and to see and realize the manifestations of those names in his life all the time. For, man can fear Allah and attain a sincere belief only if he can realize Allah’s greatness. 

            A person who can appreciate Allah as it is necessarily knows that there cannot be any power except Allah and does not fear anyone except Him. He knows that nothing will happen unless Allah wishes, which enables him to worship by turning to Allah only. When he wants to do a good deed, he does it not because of fearing the reactions of people but because he does not want to act contrarily to Allah's order. Similarly, when he decides to give up doing something, he does not give it up thinking that people will get angry with him but in order to attain Allah’s mercy and avoid His wrath.

• Allah's consent as much as possible

            A person who wants to show the sincerest attitude in everything he faces needs to seek "Allah's consent as much as possible". This order of Allah is reminded through the following verse with the phrase "strive as in a race in all virtues":

"… so, strive as in a race in all virtues. The goal of you all is to Allah..." (al-Maida, 5/48)

• Man should expect the rewards for what he does in the world only from Allah

            A person who wants to gain sincerity needs to be aware of this fact: the man should expect the rewards for what he does in the world only from Allah. If a person does something for anything except Allah's consent, mercy, and Paradise, his sincerity is broken and he is led to insincerity. If a person serves in the way of Allah for years with this thought, he will not have gained sincerity in its real sense unless he does them for Allah’s sake only. Only the deeds of worship that he does without adding anything except Allah's consent can gain him great rewards and thawabs.

• It is necessary to base everything directly on Allah’s consent.

            Even if everybody is against a person and nobody is pleased with him, it is of no significance if Allah is pleased with him. For, the hearts of all of those people are under the control of Allah. If Allah wishes, He will make them pleased with that person.

        

            On the other hand, if Allah is not pleased with a person due to his attitude, it is of no significance if everybody is pleased with him and is grateful to him. A believer knows that it is of no significance in the eye of Allah and that people’s being pleased with him will gain him nothing in the hereafter unless Allah is pleased with him. The group that will be pleased with him may consist of financially or politically powerful people. However, they are all weak beings that were created by Allah and that will decay in the grave one day, losing all of their power. Therefore, their number, support, and appreciation will be of no use in the hereafter. The one who is eternal and whose consent needs to be attained is only Allah. What will make man gain a permanent understanding of sincerity is ‘to ignore the consent of people and to aim to attain Allah’s consent’ by realizing this fact.