Living a simple life is to rise above the pressures around you and not live life like a race. It's not about lack of ambitions but lack of anxieties. It's not about being materially poor but being materially independent. It's not about being gullible but being content. Living a simple life is about living an uncluttered life. Freeing yourself from unnecessary weights and worries. Going after only the things you need and not everything you can get. A simple life cannot be easily rocked; it's like a floating board it rises above the storm.
And getting a simple life begins with looking within you. Uncluttering your mind. You need to figure out for yourself what really matter to you at each stage of your life. You need to stop letting people mentally push you around. You need to think hard for yourself. Simplicity can be hard work in the beginning as it involves getting rid of the things/thoughts you don't need. You'll be living life on your own terms and above the influence of your surrounding. You will have very few worries.
Simplicity is about living an internally rich and focused life. And it is the peak of personal development: being the you you were meant to be and nothing extra. You travel light through life and take up more adventurous journeys than most other people because you know whom you are and whom you want to be. The adventures are mostly the result of you following your own path to self-fulfillment. Of letting go of society induced worries and external weights. You find out who you want to be, all you need to be that person and pack light as you journey towards being that person.
The beauty of a simple life is that it is a full life. We are human beings not human doings. Our lives aren't meant to be dominated by activities and races. A simple life helps you be the being your were meant to be.