Journey towards self realization is an inward journey conducted via contemplation (chintan) towards our soul atman, spirit existing in our heart.
I started in search of God six years of age. By 37 years of age I finally succeeded in reaching God. A time period of 31 years multiplied by an average 10 hours of contemplation every single day comes to 113,150 hours. The time period could be more but not less.
Lying in shavasna pose of yoga in the night when going to bed I always indulged in self enquiry, Neti (not this, not this) to dissolve queries within. For all practical purposes I was all the time engaged in discovery of God.
My desire to search for God was so intense, even while walking, jogging, swimming studying, indulging in sports, even in business I was all the time contemplating on God.
The timeframe for reaching state of self realization could vary between 50,000 hours to several million hours (meaning many lifetimes). That is the time we require to dissolve all queries within. Only then we can become a pure soul atman forever.
Journey of spirituality as detailed in Bhagavad Gita is the only path to reach state of self realization. If we can do that, if we possessed willpower exhibited by Swami Vivekananda, we were a right candidate to indulge in spirituality to reach God in our lifetime.