When you practice meditation for some months (for some, a few weeks or years), you gain a piercing insight into the nature of reality, and you might find the reality much more darker and sadder than you previously thought.

But meditation will also teach you that these don't matter.

Couple that with the personal cathartic experience of your forcefully subdued gloom, sadness, worries, etc. resurfacing and making you more afraid/anxious. This happens after some days/one-two weeks.

But meditation teaches you to overcome them. After years, your sense of self will cease.

These are not trivial things, so you will do better having a learned, practicing guru and/or solid base in the Philosophy.