Life is indeed difficult, partly because of the real difficulties we must overcome in order to survive, and partly because of our own innate desire to always do better, to overcome new challenges, to self-actualize. Happiness is experienced largely in striving towards a goal, not in having attained things, because our nature is always to want to go on to the next endeavor.
Life is full of surprises and and serendipity. Being open to unexpected turns in the road is an important part of success. If you try to plan every step, you may miss those wonderful twists and turns. Just find your next adventure-do it well, enjoy it-and then, not now, think about what comes next.
When we exercise self-control on a given occasion, we win for ourselves a little credibility we can rely on the next time around. Pretty soon we develop a reputation to ourselves that we want badly to uphold. With each test that we meet, our resolve gains momentum, fueled by the fear that we may succumb and establish a damaging precedent for our own weakness.