When you are in an emotional state, your mind creates corresponding thoughts.

When you feel angry, you will seek out things that seem 'reasonable excuses' to feel angry.

When you are happy, you will seek out things that seem 'reasonable excuses' to feel happy.

I imagine it like this:

The entire world is in grey except for things that trigger your emotion.

(Isderion,CC BY-SA 3.0 DE, via Wikimedia Commons)

So you are simply much more likely to notice the yellow umbrella.

And that umbrella enters your conscious mind, reinforced with the emotion.

So if someone were to ask

Why are you feeling <insert emotion here>

Your response could be

Obviously because of that yellow umbrella!

Just look at it, it's clearly the cause for this emotion.

What you may not realise, is that the actual reason for that emotion, was something that happened hours ago.

Maybe even something that happened yesterday.

Perhaps triggered by:

• The stress of getting to work on time may linger until noon, making you irritable and impatient.

• Some smell or sight or picture reminded you of a loved one that passed away, causing lingering grief.

• ...