I've been a couch potato for my whole life, however I've started doing exercise recently.Though there might not be a significant enough change during this short time to mention now, still there are some slight changes that I do believe will make a tremendous difference in my life given time. First, I've been exercising regularly so, I think I've been a well-organized person. Second, I realized I can think better while I'm doing an exercise, specifically running. Moreover, I think after exercising I feel I'm a happier and more energetic person. In conclusion, I feel these small changes together lead me to have a good feeling about myself and going forward I'll end up me being a better version of myself.

Recovery of my past and I have started something new so that I can change myself daily

Because you said "hold your horses" you have already suggested he is exaggerating so you don't need an extra phrase.

I think as a native speaker we would probably say tomorrow is a holiday out of laziness because it is quicker than saying tomorrow will be a holiday

You can use either the first or last, the last is most grammatically correct but a native English speaker would use either