Have you noticed this? Whenever you have done some really good hard work, and finished some project or some activity, you feel so good. Its this feeling of being useful, being capable, being illustrious, being active, dynamic, energetic. If you haven’t felt so, you haven’t yet done any hard work!
Of course you can do the hard work smartly too- Put energy in the right direction, instead of the other way around, but you need to really really sweat it out, even in the right direction- and doing that with a smile is sign of success in life!
Yogah Karmasu Kaushalam :- yoga is skill in action.