mMy heart is so tired. My heart is so tired

You don't need ending punctuation in a title, but you should still capitalise the first word. "My heart is so tired" is a bit strange, but it's OK as a title I think, though this is perhaps up to personal preference.

That's because I attended a track and field match makes me ievent. That's because I attended a track and field event.

- Generally, 'because' should not really start a sentence - it doesn't work the same as なぜなら or 理由は. If you use because, it would be good to combine it with the previous sentence - 'I felt very tired because I attended a track and field event'. - You would use 'match' for a soccer match or a basketball match, but for track and field, you might say a 'race' or an 'event'. - The first sentence is in the past tense, but the second is in the present tense - you should be consistent, so this is better as past tense. - You could say 'track and field makes me tired', but 'track and field makes me it' feels unnatural (even though I understand it).

I will have a delicious dinner today. I will have a delicious dinner today.