Being content

You can try to please everyone, but at the end of the day, you cannot be friends with everyone.

You can try to change yourself to be someone else who seems to be "better", but at the end of the day, you need to be yourself.

At the end of the day, do you reflect upon what you've done wrong or think about your accomplishments?

Live in the present, not the past. Be content. You actually have more than you think. People can be greedy and want something more when they realize they are losing it, whether or not this thing may be suitable for them. You have to realize that you can't have everything, and it's ok not to have everything :)