The highest achievement a believer can attain in this word is to have peace and tranquility.  The only way that this can be achieved is when your nafs is conditioned to a point where it works in co-ordination with your ruh.  This is refered to as Nafsul Mutmainah

As believers we should strive to reach this stage of Nafsul Mutmainah through trust / faith in Allah  and through sincere supplication to Him.  Having faith in Allah  sounds simple but in reality it is difficult, especially when the trials come our way.  However, Allah  gives us comfort in Surah Fajr;

(to the righteous soul will be said:) "O soul, In  rest and satisfaction!  "Come back Thou to Thy Lord,- well pleased, and well-pleasing unto Him!  "Enter thou, then, among My devotees!  "Yea, enter Thou My Heaven!  (Chapter 89, verse 27 – 30)

This is the real jihad of the believers, conditioning the nafs to work in harmony with the ruh.  It sounds simple but when you take into account the distraction of this world it makes it a little more difficult. 

Allah  has given us examples in the Qur’an where sometimes, even pious people allowed issues of this world to create a sense of uneasiness and restlessness in them.  For example when Prophet Jacob (may Allah  be pleased with him) lost his beloved son Joseph (may Allah  be pleased with him) he wept so much that he became partially blind.  And in the end when the decree and plan of Allah  came to pass and Jacob was reunited with Joseph all the trials and headaches seemed like a bad dream. 

It is human nature to worry and sometimes feel dejected but we must remember that Allah  is our Wali (best friend) and He would never let us down and He would never give us a burden that is unbearable. If we can show patience, trust in Allah and faith that He, as a Friend is always there for us, then we will be on the Straight Path that will lead us back to Him; and one day we shall have a pleasant meeting with him.  Satan will never have that beautiful meeting with Allah  and as such he would try to prevent us from also having that meeting by testing our patience and emotions. 

Whenever you are confronted with difficulties remember what Prophet Jacob (ra) said when he first learned of the loss of Joseph (ra); “Sabrun Jameelun” – “(for me) patience is most fitting: it is Allah (alone) Whose help can be sought.”

Work towards attaining Nafsul Mutmainah so that you would not only find peace and tranquility in this word but more importantly the next.  Use the trials and difficulties to your benefit by demonstrating patience and trust in the Merciful Lord, and Insha Allah He would be most pleased with you and when the time comes for you to return to Him the meeting would be a most special and beautiful one