First: A Change of Heart

People can experience dramtic change if they first have a change of heart. 

It would be encouraging if we could only change slowly and in small steps. So here is good news. 

There was once a 6 ft. 2 in. 240lb. young man who was strong, quick, stubborn, and had a temper at times. Some would say he was a little on the rough side as he smoked, occasionally got drunk, and went to parties with a rough crowd. 
I tell this story because all this stopped. Not gradually either. But very quickly. 
One day, I asked him how, unlike so many others; who had a hard time to stop smoking nad drinking, he could do it so quickly and completely. I don't recall his exact wrods but the central point was that he didin't want something like cigarettes or liquor controlling him or his life. 

The majority of experimental research findings in psychology leads to the conclusion that our change or growth is slow and gradual. There are exceptions as observed in the adolescent growth spurt or in the "ah-ha" experience in solving a problem.  
But, the general conclusion based on observations and experiements is that there is a gradual improvement as a result of rewarded pratice. From B.F.Skinner's theories and research comes the recommended procedure for changing anothers behavior. It is to gradually reward successive approximations of the desired behavior. At first, the subject in the experiment or person in the treatment will not be able to make the complete desired response. but can ıonly make a small part of hte desired action or behvaior. Therefore, if they make a small approximation  then they should be rewarded and each subsequent reward should only be given when they make a slightly more complete approximation of the desired behavior. This is not the way to do things in a marraige or partnership. 
In contrast, when one focuses  on the spirit of another person the observable behavior and actions become less important. Instead how the spirit feels or perceives is the critical and most important element. Behavioral change follows a change in the spirit. Fortunately, changes in the spirit can occur quickly, dramatically, and completely. A person's behavior changes quickly and markedly to be congruent with teh change in the inner spirit. This is the ideal way to bring about change in marriage. 
There is no disputing the fact that extenal pressure, rewards, and a combination of carrot and stick can change behavior. The disadvantage is that the behavioral change will usually be given grugingly, slowly and  only enough to gain the rewards or avoid the punishment. When a person's heart is touched, behavioral change will be spontaneous, dramatic and enduring.