How to be happy always?

How to be happy always?  Is happiness associated with circumstances?  A baby enjoys with a empty pot/box happily.  She plays with a small toy and amusingly.  Why?  It was new for her and she enjoys every new moment.  a few years later same things become boredom for her.  She was quite happy with the small things and now she started associating with new dolls,  new friends etc.  After a few years, she then changes her happiness by associating with marks,  grades,  good remarks, complements. Later she changes her happiness by associating with pubs,  discos, comforts, luxuries etc.  Happiness is different for a poor girl/boy and rich boy/girl. Poor associates his/her happiness with rich stuff and rich associates happiness with poor stuff.  So happiness=association with what we do not possess, what things we never experienced.  Always changes with time.  But if we can still enjoy those little moments by watching sunrise, sun set,  by watching ants, by playing with kids, all the things that made us happy a few years earlier? Then no one can make us sad irrespective of circumstances.  Because these little things are always with us for life time. Nature is with us all the time.  Just the way we associate with happiness changes our lives for ever.  We no longer be unhappy if we do not earn money,  we no longer unhappy if we do not get position we wanted,  we no longer be unhappy if we do not get respect from others. So simple equation is to stay happy is associating with little things in life which cannot be destroyed or always with us.  Eg:nature.  This is the sole reason for Hindu dharma treats nature as goddess. So one can feel that goddess with us all the time and stay happy. Be happy for ever.

In a nutshell, current situation is like this.

Infant: everything makes him happy as he keeps wondering what is this world, insects, rocks, sun, living beings,  non living beings everything make them happy.
Child up to 5 years: small things, waste papers, waste materials, whatever we think they are useless,
6-15 years: marks,  ranks, complements from people, sports, recreational activities, big toys, cycling etc
16-22years: love, beauty, alcohol, drugs, girls, parties, anything that gives them complete freedom.
22-30 years: career, job,  outings etc
30-45 years: settlement, own things like own house, marriage, kids, making them happy - - anything related to status, if someone praises about his status he feels proud and happy.
45-60 years:, kids happiness, their life, devotion--mostly selfless, so anything related to their family etc
60-75 years: only God

But nature is there all the time. If we can be happy by just seeing the nature,  people,  then there cannot be unhappiness. Or we can associate happiness with what we have already possessed rather than what we do not possess or things depend on someone.