Let's start with a modest goal. Say you aim to earn a total of $300 (US) a month in affiliate commissions and AdSense revenue. Imagine what you could do with that money. A holiday? A better lifestyle?
I've kept the amount low, because it's important that you believe you can do this. Achieve small successes first, see the money in your hands or in your bank account, and then increase your goals.
Next step : Find your niche