Sentence 1: I went hiking yesterday in the mountains. 
 Sentence 3: I could not believe how I felt 
 Sentence 4:  I had to take a long pause 
 Sentence 5:  Thankfully after a while I was able to keep going 
 Option 1: I trekked up the mountain with no difficulty. 
 Option 2: As I trekked up the mountain, I started to feel out of breath.