When you are young, you have your whole life ahead of you. As you get older, you start to lose some of your dreams. However, when you are older you have the advantage of memories, which youth does not.
I'm 57 years old now, and I've watched my body age from a strong young teen into a relatively healthy "senior citizen." I would love to be able to have the physical durability that I once had and the youthful zest for life that tends to cool a bit as one ages. However, nothing can substitute for life's experiences, and that is one area in which youth can never surpass an adult.
The advantages are that your body is young and still works right and that you have your whole life and all its possibilities ahead of you. The disadvantages are that you have more uncertainty. You don't know if you'll find a spouse. You don't know if you'll find a good career. You have possibilities, but you also have more worries.
We go through many stages in life.
"Each stage brings with it bodily changes ranging from continuing growth during childhood through early adulthood, slight declines during middle adulthood, and often significant loss of functioning in late adulthood" (eNotes).
Summarizing the advantages of one stage over another is no easy task, but here are some thoughts on advantages and disadvantages of being young.
Some of the advantages of youth are physical in nature. Young people are able to perform most physical tasks with relative ease and recover relatively quickly after exertion. Older people may take days to feel back to normal after a day of intensive physical exertion.
Older people often reflect on this aspect of youth, especially when bending down to pick things off the floor. Consider also that most Olympic athletes are under twenty-five years of age. A majority of professional athletes are similarly young. Only the best in any sport are able to carry on past the flush of youth through skill, smarts and tenacity. The average career span of a professional athlete is actually only a few years, which speaks to the importance of the physical benefits of youth. (Only the young can perform the tasks, on average.)
Also, young people will tend to have more family of older generations. As people age, their older relatives die. This is inevitable, but it means that young people have (1) more chances to be taken care of by elders and (2) more opportunities to receive instruction from elders.
While older people are generally more knowledgeable and wiser than young people (which is a disadvantage for youth), young people have more access to the wisdom of elders than older people do. So, the young may not be wise but they can ask questions and learn from others in the family more easily than older people might be able to.
Young people have the power to dream in ways that probably outpace the dreaming power in older people. Untested potential means that young people do not know the limits of their abilities or of their will-power. However, young people may not know that will-power and follow-through are keys to making any dream come true.
Young people may have a less developed sense of who they are in the world and often are given less status/stature in social situations. This can lead to some of the rebelliousness of youth (when people want to prove their worth and/or show that they are potent beings, capable of taking action and making decisions for themselves).
Young people are often more challenged to find jobs that pay well. (This may be true largely because young people have less experience than older people.)
Young people have fewer experiences to reflect on and have had less of a chance to realize what is worth reacting to and what might be best left alone. If maturity is a means of placing proper value on various aspects of one's life and so caring about the right things and letting other things go, then young people are at a disadvantage because they have not had enough time to do the work of deciding how to place things on the scale of importance.
“Life isn't about finding yourself. Life is about creating yourself.”
― George Bernard Shaw