It depends on what your view of success is also. I used to think success was promotions and pay rises in my job, i worked so hard i eventually triggered a genetic chronic illness. Sometimes it's not whether you can handle it but whether it is adding or taking away from your life and how you enjoy it. Now success to me is achieving goals that make me happy. Doing things that are meaningful to me whilst still being able to provide for myself and my family. With my illness sometimes it's just being able to do a certain physical activity. I totally agree with the lazy part, pushing yourself to succeed in whatever it is and then achieving it will always give you more incentive to keep going and has always given me a proud feeling.