There is no simple or fast way that is going to provide a quick save to a marriage necessarily but the best way to do it in the least amount of time possible is to completely put your own agenda aside. Do this in all of your interactions with your spouse and by providing unconditional, positive, loving, caring, understanding, patient, and nonjudgmental attention and support. Truly listen to your spouse and provide her or him with the space to really express whatever it is she or he is needing from you and the relationship to be able to move forward. Then be willing to change and start changing immediately.
I am not sure why you want to do it in less time - because you want to make sure that it is not too late, or because you don't want to put in the time needed? Anyway, here are some tips: tell your spouse you love them, often; learn to say sorry and mean it; don't criticise; don't have friends of the opposite sex; be fully committed to one another; love each other even when you don't really like each other; don't try to change your spouse; focus on improving yourself and your marriage will improve.