Your tonight/tomorrow plans may never but death is one of the few things in life certain to occur. (100% certainty!) So acting in the way like you'll never meet the death is a huge mistake. We should all live by the commandments of God and always do good/right actions, before the time comes that we regret every moment of our lives. (May God forbid)
They will say, 'If only we had really listened and used our intellect, we would not have been Companions of the Blaze.' (Surat al-Mulk: 10)
We have warned you of an imminent punishment on the Day when a man will see what he has done, and the disbeliever will say, 'Oh, if only I were dust!' (Surat an-Naba': 40)
Right actions are deeds, which are performed utterly in order to earn the good pleasure of God. For a deed to be a "right action", it should be performed only to please God (not to be known as a "good person" by others).
“Not so! All who submit themselves completely to God and are good-doers will find their reward with their Lord. They will feel no fear and will know no sorrow.” (Surat al- Baqarah: 112)
God gives a detailed account of virtuous, blessed behaviour and attitudes in the Qur'an. The typical attributes of an individual who is sincerely devoted to God and who is aware that he will be judged are:
Repelling evil with good,
Having mercy for believers,
Not being led astray by rage,
Engaging in good deeds for no price or reward,
Remaining consistently temperate in one's approach to people
Avoiding ridiculing people because of jealousy and selfishness,
Speaking graciously to people,
Keeping promises and trusts,
Being a reliable witness,
Avoiding vain talk and trifling,
Settling matters wisely
The only way to avoid regret is to submit to God while there is still time and follow these virtuous, blessed behaviour and attitudes to comply with the commands of God.
We have to keep in mind that day no one's regret will save him from God's wrath.
“Respond to your Lord before a Day comes from God which cannot be turned back. On that Day you will have no hiding-place and no means of denial.” (Surat ash-Shura: 47)