Sometimes saying 'yes' to others means saying 'no' to yourself.
Helping out others, saying yes to everything, making others happy is a very kind gesture. Sometimes to please people we put them ahead of ourselves, whether it is taking other's responsibility at work when you are already packed with your own or going out with friends when your body craves rest. But at what cost?
Continuously catering to others while allowing your needs and desires unaddressed left you unhappy, regrettable in the end. It's important to help ourselves first before catering to others.
So, learn to say No with grace and make healthy boundaries for yourself.