In Romans 15:3 - it is written about Jesus that "He did not please Himself". He always denied Himself. Thus He pleased the Father at all times.
Pleasing oneself can be done in many areas of one's life - for example, in the area of eating. Consider a situation where, even when you are not hungry, you decide to spend some money to buy some tasty snacks to eat. There is certainly nothing sinful or wrong in that. But it speaks of a certain way of life. Because you have money, you buy what you like, whether you need it or not. You do what pleases yourself. If you feel like buying something, you buy it. If you feel like going somewhere, you go. If you feel like sleeping late, you just sleep late. What is the end result of living like that, even if you go regularly to the meetings and read your Bible every day? You may not lose your salvation, but you will certainly waste the one life that God gave you to live for Him.
Another brother however acts differently. He decides to discipline his body. When he is not hungry, he decides not to eat anything unnecessarily. He decides never to buy any unnecessary things for himself. He decides to get up 15 minutes earlier each day to spend time with God. When someone speaks to him angrily, he decides to reply gently. He decides to remain in love and goodness always. He decides not to read certain news items in the newspapers that will stimulate his lusts. In every situation, he decides to humble himself and not to justify himself. He decides to give up certain friendships that are influencing him towards the world. Through constantly deciding to deny his own will (what pleased him), he becomes strong in his will to please God alone.
What did he lose by not buying that unnecessary thing, or by getting out of bed 15 minutes earlier, or by giving up his human sense of dignity and asking for forgiveness? Nothing. But think of what he has gained!
A man like that, who is consistently faithful in the little things, will in a few years' time become a trustworthy man of God - not because of the Bible-knowledge that he possesses, but because of his faithfulness in the little decisions he takes in life not to please Himself but to please God.
Don't be weak-willed then. Exercise your will to please God at all times. Mature Christians are those who "because of practice (in exercising their will in the right direction through many years), have their senses trained to discern good and evil" (Heb. 5:14).
Consider an illustration: Two fat men go to a doctor to remove their flabbiness. The doctor gives them a course of exercises for the next twelve months. One man goes through the discipline of those exercises consistently every day, and slims down and becomes strong. The other man does the exercises for the first few days and then slackens off and finally gives up altogether. His pot-belly gets fatter and fatter with his indisciplined ways, until he finally dies prematurely. This is an illustration of how we can either make our wills strong to do God's will, or leave them flabby and weak for the devil to exploit.
I remember reading once of a young servant of the Lord who felt that he had been watching too much television (even though he had been watching only clean programs), and who decided one day not only to sell his TV set, but also to use the time that he had spent watching TV, in prayer every day. As a direct result of that little decision that he took - and maintained - God gave him a ministry that blessed thousands. Those who see nothing wrong in watching clean programs over TV, find that God does not entrust them with much - for He is a rewarder of those who diligently seek Him and there is no partiality with Him.
Yes, you are what you are today because of those many, many little decisions that you have taken in relation to either denying yourself or pleasing yourself in the areas of food, money, sleep, reading, etc.,
So forget the blunders that you have made in life. Repent radically of your sins and be wholehearted in the days to come. God forgives you and blots out your past. Don't mope over your failures now, or you will be a drifter in the future too. The memory of your failures will help you to recognise that you are what you are only by the grace of God. It will also enable you to keep your face in the dust at all times before God.
Determine that you will become a true man/woman of God.