Yes, it is possible for you to change with God's help. And because it's possible to change, there's no reason for you accept defeat and stay the way you are.
The first step is to realize that you can't battle temptation on your own. You need God's help. The first step in finding God's help is to ask Him to forgive you for your sins, and then to open your heart and life to Jesus Christ. God loves you and doesn't want you to spend the rest of your life in sin and failure. He loves you so much that He sent His only Son into the world to die on your behalf. Commit your life to Christ today, and thank Him every day for His forgiveness and love.
Then ask God to give you a new desire to turn your back on sin. This won't necessarily be easy; the devil will do everything he can to defeat you. But listen: You are not alone! Christ lives within you by His Spirit, and when temptations come, turn to Him and seek His strength and help. God has promised, "I will give you a new heart and put a new spirit in you" (Ezekiel 36:26).
In addition, deal with temptations in advance. For example, if certain people or situations tend to pull you down, avoid them. You can trust God's promise: "God is faithful; he will not let you be tempted beyond what you can bear. But when you are tempted, he will also provide a way out so that you can stand up under it" (1 Corinthians 10:13).