Could you suggest a meditation technique for me?

I'm 21 years old, and I have more white hairs than naught. I am a very tense individual, and have a hard time relaxing, especially since I kicked my weed habit. At the same time, I feel like I am lazy, which is a quality I THOROUGHLY DESPISE. Is there some method of self-discipline/concentration I can use to increase my energy and confidence, while at the same time helping me relax and bring me out of depression. Any suggestions are greatly appreciated.