It is crucial to understand that when we die, it is only the death of the human body; the spirit (our soul) lives on. When we die our soul loses its physical connection with the world which we know when we are alive.
Everything we do in this life, we should do with the conscious awareness that the consequences of every action will carry on after we leave this world; that our soul will bear the burden of it.
With this thought should come a realization; what is the purpose for us to be in this world!
Inner peace and happiness actually comes from a clear conscience which keeps our soul at peace!
Let me elaborate this point with an example – If we help someone in times of need, or give food to the poor, these actions will not result in any monetary gain, but these actions will fulfill us at a spiritual level because our soul will reap the rewards of these actions, even after our exit from this life. On the other hand if we cheat or steal money from someone, this action might result in a temporary gain of a monetary benefit, but will lead to a guilty conscience - which is the unrest of our soul. It is our soul which will have to face the consequences of these deeds.
So whatever we do in life, please do keep in mind that every action will result in a positive or negative reaction from our soul. So if you truly want to create a life full of inner peace and happiness, be fair with others, keep your word, and be kind and generous. This approach to life will rid us of corruption and dishonesty & will steer our lives in the direction of success and prosperity.