Feeling under pressure before an exam or during an uncertain period is a common human response. A little stress can even help us meet a challenge; too much can affect both mind and body. Not every difficult moment points to a mental disorder.
WHO describes mental health in terms of being able to face difficulties, develop abilities and take part in life. It is not a fixed state: it varies along a continuum and is also shaped by relationships and the environments we live in. It is not simply a matter of willpower.
That does not mean ignoring suffering: persistent distress that disrupts studying, work or relationships deserves professional attention. Recognising difficult emotions as part of being human and taking someone who is struggling seriously are compatible. There is room for both, without turning every feeling into a diagnosis.