I thought about going for a walk nearby , but with so much work waiting for me, I had to abandon the idea.

I am also preparing for an exam as well, and I hope to achieve a good score through my hard work.

Your original sentence was correct, but it was redundant. Since you used "also" already, immediately using "as well" is unnecessary and should generally not be used in order to sound more natural. The removal of the "I" is less necessary to sounding natural than removing "as well", but since you started the sentence with "I", you don't need to use it again after the "and'.

I'll cheer myself on and strive for my goal s!

"goal" would be correct if you only had 1 goal (if this is the case, then you can disregard that correction). The saying "strive for my/your goals" is an extremely common phrase in English.

It's sunny today, Bbut there's a faint haze in the air --

I thought about going for a walk nearby , but with so much work waiting for me, I had to abandon the idea.

No space before a comma, one space after a comma

I am also preparing for an exam as well, and I hope to achievereceive/get/earn a good score through my hard work.

Also = as well. Using both is redundant.

I am cheering myself on ands I strive towards my goal !

The original sentence was a bit incomplete