Not to be feared
Ageing is a natural process that cannot be avoided. We are like a butterfly that has many stages in its development, ageing and getting old is just one of the many stages we go through in life. Nothing on this earth was made to last forever except for love. From trees to the earth we walk on, everything has an end in its physical form. We need to accept this natural process and learn to enjoy ageing like we enjoyed other stages in our life (e.g. childhood and teenage years).
You must stop worrying about what you will look like and how you will die when you get old and do your best to enjoy life and all that it brings. This is not to say that you should mistreat your body with poor nutrition but quite the opposite, you should love yourself and by doing this, give your body the best food and exercise that is available to you.
The way we age is a reflection of respect we have towards ourself. When we look after ourselves we maintain our lovely bodies by exercising, eating well, and grooming. Every thing on this planet is going through a natural cycle, some longer than others. Enjoy the time you do have.
Learn to accept the beauty behind the age you are currently at. This includes the wisdom, understanding and knowledge you have gained up till now, this will change day by day, week by week, and year by year! Rejoice in your existence and expression.