Being bored and living a comfortable, boring life where you are able to have all of your basic needs met and are free to do what you want with your life is such a luxury compared to the lives of the majority of the people on earth. Here is a purpose for you: use your privileged life to help other people. Volunteer for or raise money to support organizations that help people - locally or global. Do any small or large thing to help another person. Any group of people or any individual person. Pick at random if you don't specifically care about anything or anyone.
And while you're at it, why not do the work that needs to be done to ensure that you keep experiencing the benefits of living a stable, healthy, boring life? Not studying and not doing anything to ensure your continued health and financial security will pretty quickly lead to the things you take for granted in life being taken away from you (health, a comfortable place to live, freedom, having enough to eat, having friends / supportive family). Maybe once you personally experience how shitty life can be, it will help motivate you to do something for yourself and/or others. Hopefully at that point it won't be too late.
You're not going to magically "want" to do the work that needs to be done. People are not born with "purpose, duty, responsibility". They decide that they want to live comfortably and for their lives to mean something or that they want to make some positive change in the world. So, they make goals and they work toward them. Then they do the everyday boring, tedious, difficult work involved in making the lives they want for themselves - this is called discipline. Having Purpose, duty, and responsibility and being "useful" are things that describe you when you decide to the boring and difficult work behind ultimately doing something good for yourself and/or others, even when you don't have some innate sense of motivation to do these things.
Have some gratitude, help other people, and do what needs to be done ensure your long-term health and well-being.