You are on this planet for a very unique and big purpose, not just to eat, sleep and talk. Always remember that you are here for a greater cause and don't lose your smile. For our own growth and strength, we need to follow some rules. They are called yama and niyama.
The first is ahimsa or non-violence which unites you with the whole creation. A practice of yoga, of realising that everything is a part of you is ahimsa.
The next is astheya - not missing what you don't have at this moment. Totally accepting what is and not regretting is astheya.
Then comes brahmacharya which means moving beyond small identifications. Being not interested in shapes and forms of the body and seeing the infinite is brahmacharya.
The fourth is aparigraha — not taking what people have to give you. You often take much more insults than compliments people give you. Even if someone is giving you garbage, you don't have to take it.
There are also some rules that ensure peaceful living in society. And then there are five rules for your inner development. The first one is cleanliness or shaucha -- keep yourself clean and wear clean clothes. Be clean from within. Leave anything that doesn't sound right and bothers the mind.
The next rule is santosha or contentment. Be happy. If you don't take a step towards being happy, nothing in this world can make you happy.
The third is forbearance or tapa. Tapa means putting up willingly with something that is uncomfortable. If you were asked to sit continuously for ten hours, you would never do it. But suppose you have to travel in the plane for a long time, you have no way out and willingly sit with the belt. Willingly accepting opposites is tapas. The rule is that change whatever you can, but accept if you cannot.
Then comes self-study of swadhyaya. Observe your mind and see what is going on. If you are feeling bad, just observe and you will start feeling good again. When you observe, all the feelings, good, bad, will change.
The last rule is ishwara pranidhaana — love of the Divine. Surrender to the Divine when you feel you are totally helpless and offer your feelings.
These rules make you very strong and complete. To be established in these rules, you need spiritual practices. Do some meditation, sadhana and service and keep your smile!