Wisdoms from Ecclesiastes

I am in the middle of reading Ecclesiastes and I really love this book. Below are some wisdoms I extracted which is very relevant to my life. I hope you enjoy them as well.

Eccl 7:10 - Don't say, "Why were things better in the good old days?" It isn't wise to ask that kind of question.
I think this verse is warning us against dwelling in the past - the good old days. We must not love our past. We must always look forward to the next best thing to come.

Eccl 8:6 - There's a proper time and way for people to do everything. That's true even though a man might be suffering greatly.
We have to do everything properly when required even though we might be suffering greatly from things such as personal issue, trouble, bad mood, etc...I know this is tough but by God's help it can be trained. This is especially important in our professional job.

Eccl 8:9b - A man sometimes makes life hard for others. But he ends up hurting himself.
We must not make life hard for others. Otherwise we will end up hurting ourselves. I think this is basic rule for building good relationship but we must be careful not to subtly fall into the trap of making life difficult for others.

Eccl 8:14-15 - Here's something else on this earth that doesn't have any meaning. Sometimes godly men get what sinful people should receive. And sinful men get what godly people should receive. Here's what I'm telling you. That doesn't have any meaning either. So I advise everyone to enjoy life. A man on this earth can't do anything better than eat and drink and be glad. Then he will enjoy his work. He'll be happy all the days of the life God has given him on earth.
I think Solomon is trying to tell us the importance of enjoying and living life to the fullness everyday. Don't ever live our day by comparing our "righteousness" with other people and the "reward" we are supposed to receive for being "righteous". We will end up being very unhappy because God does not promise fairness. He only promised justice. Our duty is to obey the Lord and follow His lead everyday. We must not use our wealth and status to measure our level of righteousness because such formula does not exist.

Eccl 9:10 - No matter what you do, work at it with all your might. Remember, you are going to your grave. And there isn't any work or planning or knowledge or wisdom there.
No matter what we do, we must work at it with all our heart and might. We can't do it when we are in our grave. Isn't this make perfect sense?