You feel safe inside your comfort zone when you say no, but you do not have to fear to be rejected, your life can expand and deepen when you start affirming, the yes allows you to open your have helped me to be happier in my life.
The morning is the most important hour of the day, if you spend an hour a day to do your favorite things you will be happier in life, healthier and more motivated than you ever felt, trying to be perfect is setting the bar too high and maybe impossible to reach, you will end up reducing your self-esteem, not being yourself, always trying to change for others does not make you feel good at all, pessimism can also limit your life and stop it.
If you do some kind of exercise, even if you are walking or stretching during some time of the day it will make a big difference in your general health and longevity, it allows you to feel full and full of energy, concentrated and committed, you can change your routine a little bit every day , read or get positive and inspiring material, find something that excites you and that you want to read, immersing yourself in a positive material makes your subconscious more affirmative.
You can build walls and glass ceilings where there really is not any, it is to say yes, a more optimistic way of thinking can open your life, do not cling to the past and the pain that is there let go and look at the now and the future it is essential to find more happiness in your life, it is not always easy and it takes time, but there are always some things that can make it a little easier, live your life completely despite the blows and bad times, sometimes it's easier back off.