“Happiness in the present moment embraces two very distinct kinds of things: pleasures and engagements.
Pleasures are delights that have clear, pleasant sensory and strong emotional components ― ‘raw’ feelings. They involve little if any thinking.
Engagements, on the other hand, are activities we very much like doing, but they’re not necessarily accompanied by any pleasant raw feelings at all. Rather, we become immersed and absorbed in them, and we lose self-consciousness. They involve quite a lot of thinking and interpretation.” 
“Pleasures are immediate, momentary, and need little or no interpretation. Touching, tasting, smelling, seeing, hearing, and moving can directly evoke pleasure.
In other words, the sensations themselves are the good part.
When you’re covered with muck, a hot shower feels great. Both a spring day and sitting down in front of a fire on a snowy evening are examples of pleasures.” 
more examples of pleasures:
• eating your favorite dessert
• smelling your favorite scent
• listening to a new, catchy song
• looking at a beautiful combination of colors
• getting a massage
• scratching an itch
• drinking water when you’re really thirsty
• finally using the bathroom
• ingesting nicotine, alcohol, heroin, etc.
• sex (which can also be an engagement)
“Despite the delights they so reliably bring, however, it’s not easy to build your life around pleasures, for they’re all just momentary. They fade very rapidly once the external stimulus disappears, and we become accustomed to them very readily (habituation), often requiring bigger doses to deliver the same kick as originally (tolerance). Many even have negative aftermath (addiction).
Rapidly repeated indulgence in the same pleasure doesn’t work. It’s only the first taste of French vanilla ice cream that gives you a buzz. The pleasure of the second taste of ice cream is less than half of the first, and by the fourth taste, it’s largely just calories ― and once the caloric needs are sated, the taste is little better than cardboard. Unless you space these encounters out sparingly, pleasures like these are enormously diminished. This process is called habituation. It’s an inviolable neurological fact of life that neurons are wired to respond to novel events and not to fire if the events don’t produce new information. We notice events that are novel and disregard those that aren’t. The more redundant the events, the more they merge into the unnoticed background.
Ultimately, it’s best to spread pleasures out ― to allow more time to elapse between them than you normally would ― and to try to find the optimal spacing that keeps habituation at bay.” 
“In ordinary English, we don’t distinguish between pleasures and engagements, which muddles together two different classes of the best things in life. We casually say that we ‘like’ caviar or a back rub, as well as saying we ‘like’ playing volleyball or reading. ‘Like’ is the source of the confusion. The word’s primary meaning in all these cases is that we choose to do these things over many other possibilities. Because we use the same word, we’re inclined to look around for the same source of the liking, and we slip into saying, ‘Caviar gives me pleasure,’ and, ‘Reading gives me pleasure,’ as if the same positive emotion existed underneath both as the basis of our choosing.
Rather, with engagements, it’s the total absorption it produces that defines liking these activities ― not the presence of pleasure.” 
“Being ‘in the zone’ is what psychologist Mihály Csíkszentmihályi calls ‘flow’, using this term to describe the experience that someone has while being totally absorbed in the doing of something. He defines flow as being completely immersed in an activity ― the ego falls away, time flies, and every action, movement, and thought follows from the previous one, like playing jazz. Your whole being is involved, and you’re using your skills to the utmost.” 
“Flow is the mental state in which a person performing an activity is fully immersed in a feeling of energized focus, full involvement, and enjoyment ― an ‘optimal’ state of consciousness in which we feel and perform our best.” 
“When do you find yourself doing exactly what you want to be doing and never wanting it to end? Is it painting, or playing volleyball, or speaking before a group, or rock climbing, or listening sympathetically to someone else’s troubles?
Playing a close game of tennis that stretches one’s ability is enjoyable, as is reading a book that reveals things in a new light, as is having a conversation that leads us to express ideas we didn’t know we had. Any piece of work well done is enjoyable. None of these experiences may be particularly pleasurable at the time, but afterward we think back on them and say, ‘That was fun,’ and wish they’d happen again.
Here are the components:
• the task is challenging and requires skill
• we concentrate
• there are clear goals
• we get immediate feedback
• we have deep involvement
• there’s a sense of control
• our sense of self vanishes
• we lose track of time, time flies by” 
“People rarely succeed unless they’re having fun in what they’re doing.” 
“That’s the way you learn the most ― when you’re doing something with such enjoyment that you don’t notice the time passing.” 
I can think of one particularly memorable example of ‘our sense of self vanishing’. In college, after finishing a long, difficult exam, one girl said to another, “I forgot I existed.”
“Flow occurs when our skills match the challenge at hand.” 
[Pannenkoek] “There’s a sweetspot that leads to flow. If the activity is too easy, you become bored. And if it’s too hard, you just feel frustrated or overwhelmed.”
“Humphrey’s Law: Conscious attention to a task normally performed automatically can impair its performance.”  This is sometimes related to flow, or more specifically the lack of it.
“Furthermore, engagements generally don’t habituate as easily as pleasures do.”  In fact, there’s a sense in which engagements can reverse-habituate ― the more time you put into them, the more enjoyable they can become.
“One theory of mine is that, when we partake in pleasures, perhaps we’re just consuming. The smell of perfume, the taste of cake, and the feel of a scalp rub are all high momentary delights, but they don’t build anything for the future ― nothing’s accumulated. In contrast, when we’re engaged, in a state of flow, perhaps we’re investing ― and absorption, the loss of one’s sense of self, and time flying by are evolution’s way of telling us that we’re stocking up psychological capital for the future. For example, chess sharpens your thinking mind, creative pursuits sharpen your skills as an artist, etc. In this analogy, pleasure marks the achievement of biological satisfaction, whereas engagement marks the achievement of psychological growth.”