Time, for some people, has a way of correcting itself and redeeming those who work hard for lost time. People who don't give up on life, often emerge into a better version of themselves.
There is nothing wrong with wanting to improve yourself. In fact, to progress in life requires you to change and grow into a better understanding of your different circumstances. The only person that you should ever compete with is who you were yesterday.
Many times when life knocks people down, they don't get back up. They stay on their knees and crawl through the rest of their lives.
Then there are the people who are knocked down but say "I am going to give life another try."
To reinvent yourself starts in changing your mindset. You all know that I am a huge proponent of positive affirmations. Simply saying "I am (positive word or sentence) changes the direction of your life for the better. It helps to practice this daily or a couple times out of the week if you can. There are many other spiritual practices that you can do to help with the changing of your mindset such as prayer (and bible reading if that's what you do), meditations, gratitude, and visualization.
As within, so without.
Taking care of your body is an absolute must. This is the only body you are given, so you must take great care of it. You can accomplish this by drinking plenty of water, eating healthy foods and working out.