English is very important language at this time. There are many things that can be a motivation for why you should learn it. We are also required to learn English, because to enter the top university in the world we need English. For example, is Oxford, Harvard, Cambridge, etc. They have high standards for determining which college students are worthy of studying there, but it doesn't rule out the possibility that we can study there.
We need to know too if English is the language of the world's great leaders. For example, leaders of the UN, WTO, UNICEF, NATO, etc. They are all proficient in English and is used to giving speeches in front of many people. Surely they have come a long way to become that great. English is also the language of writers of classical literatur, history, etc.
English indeed allows us to get to know popular culture, for example, Hollywood, western music, dance, food, musical instrument, etc. It would be great if we could get to know world culture at large. It also makes it easier for us to adapt to new environments. So to know the wider world you need English.
Learning English is very easy at this time. English has simple alphabet and itself is the first step in learning English. Learning English should be done from an early age, because the benefits are so many. So, there is no reason for us no to learn English.