Doing your best means trying your utmost, thus putting in your all is essential. Skipping out on putting in your all might be the difference between success and failure, therefore doing your best means putting in your all to achieve your goals.
In other words, doing your best means giving it your all.
The meaning of doing your best has been changing over time. In early times, it meant using your best efforts. If you spent all your money on an attempt to win the lottery, then that would be doing your best. These days, however, it means fulfilling a duty or obligation. If you go to a party and drink too much, then that is not doing your best. At work, if you do not put in a full day's effort, then that is not doing your best either.
Thus, doing your best means meeting a duty or obligation and being honest with yourself about what you can and cannot do.
Remember, doing your best is not the same as making an effort. If you make an effort but still fail to meet your obligations, then you have failed doing your best.
For example, if you try hard but fail to pass your exam, then that shows that you have not done your best.
When you get sound counsel, you should always do eight things: absorb it and pass it on.
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