After contemplating this and really searching for the answer, it will emerge that the way for us to benefit beings most effectively is to attain buddhahood ourselves. By doing so we will be in a position to be of benefit to innumerable beings. When we realise that there is a means for us to attain our goal we will generate the determination to attain buddhahood in order to be of benefit to other beings. This is where we fulfil the second criterion of bodhicitta, which is the aspiration to achieve buddhahood for the sake of all beings. Thus we fulfil the two criteria of bodhicitta and our erstwhile compassion has transformed into bodhicitta. From this point onwards, all of our virtuous conduct will conform to the scope of the Mahayana motivation.
Depicted from "Guide to the Four Preliminary Practices 1 - Part 8" April, 2015, Vancouver, Canada