Bhagavad Gita 2.38

Holding pleasure and pain, gain and loss, victory and defeat as equal, prepare for the work in front of you; thus, you will not incur wrong.

सुखदुःखे समे कृत्वा लाभालाभौ जयाजयौ ।
ततो युद्धाय युज्यस्व नैवं पापमवाप्स्यसि ॥

sukha-duhkhe same kritva labhalabhau jayajayau |
tato yuddhaya yujyasva naivam papam avapsyasi ||

Holding pleasure and pain, gain and loss, victory and defeat as equal, prepare for the work in front of you; thus, you will not incur wrong.

True well-being is not faking happiness. It is finding enough inner stillness to take the very next step in your day, regardless of whether you are facing a small victory or a deep disappointment.