I think happiness is a process rather than a choice. Dr. Jordan Peterson explain it in his videos very well.

However the ideological sense of this term that we used to see it is a choice yes. In our minds we think what it the ideal of happiness? and we use fell happy or not based on that criteria. Therefore if we change what the criteria we must fulfill to be happy we can sense the ideological happiness all the time.
And some of that criteria could be something so simple like walking.