Is it effective if I only do meditation for 15 minutes?

Yes, the more you practice genuine meditation, the more you will progress.

You can think of it like.. You are the light, and as you meditate, you are touching more and more of creation, increasing your awareness of it, and also you are becoming more and more aware of who you are as the light.

The result of meditating regularly is an increasing desire to know who you truly are and be who you truly are, since you will be getting more and more aware of who you truly are.

When we experience greater beauty, we never forget it. We always want to create at least that level of beauty in our lives, because now, our minds know that it exists. And somewhere within, we know that we can experience an even greater beauty when we keep going. This desire might be buried deep, but the more we meditate, the more we uncover it. So, our desire evolves to become keener and keener, we want to focus sharper and sharper to who we truly are and we realize we can. Think of it like discovering what is best in life at your own desired pace, gradually understanding that you are the source and container of it all, of every possible thing.

No need to rush, no need to feel that you need to be someone else than who you really are. Just practice sincerely as much as you desire to practice. It will be effective.

Choose with your own free will. See for yourself as the awareness. That is meditation.

Meditation will make you aware of your suffering as well. You were unconsciously suffering, but now you will start to be conscious of it and you will be seeing how to be free of this suffering as you learn to live as who you truly are.

Here is an answer that can give further perspective:

From Lincoln Gergar’s Facebook Wall (26/02/2020): https://www.facebook.com/lincoln.gergar/posts/10216518150886719