I am not happy, I am not satisfied inside. I don't know what to do in my life and it's purpose. I am 25 now. I lost my life. What to do?

Spend a month without passive entertainment.
What is passive entertainment?
  • Watching movies, cricket, serials, songs, porn etc.
  • Reading novels and newspapers.
  • Masturbation, sex etc.
  • Surfing social websites like facebook.
  • Doing anything which is fun but does not involves you intellectually or creatively.
Now, why should you avoid passive entertainment? Because they tame you. They give you joy and keep you going with a life that sucks. You first get brainwashed during your day and work, and when you finally have time for introspection or thinking, you compensate the bad day through passive entertainment which makes your sucking life a little comfortable and you find a reason to live. You get tamed by society and its expectations. You work hard during day and watch porn in free time. You compensate. You do not revolt.
Or maybe you do. That is why you posted this question.
Now, what will happen when you give up passive entertainment? You initially feel emotional shocks. You were addicted to passive entertainment, bollywood-hollywood bullshit too much. But slowly, you will become stable. Your life will appear before your eyes in its untinted ugly form, as mine appears before my eyes. But without stimulations from passive entertainment, your life will suck more. There will be no joy, no passive entertainment, no reason to live.
And then, you will have to find the reason. You will start doing small things that give you joy. If you loved trekking before, you will become crazy about it. If you loved painting before, you will start spending nights doing it. If you loved mathematics, your brain will start storming with ideas.
People will start calling you lunatic, but that’s what they call all extraordinary people.
Give up passive entertainment. Find out yourself. The real one.