I often feel that learning languages has something in common with learning new sports. 

Of course there are some people who are naturally good or bad at taking up new languages and/or sports, but everybody can improve their capabilities by practicing. Without practice, nobody can be an expert.
In addition, we will have good days and bad days in the process of progress. Our efforts do not guarantee constant improvement. Sometimes we have a frustrating time due to will become frustrated by our poor performance, after we started especially if we were just starting to feel confident through our signs of progress.
I'm afraid that there is no goal in learning languages just like in practicing sport. It seems to be necessary to enjoy the process itself to and to continue our walk a along the winding road of learning.

I agree. It's important to set easy goals along the way to achieving your grand goal of speaking fluently! You write very well. Some of your word choices are really great, for example: "process of progress" and "the winding road of learning". I didn't really need to make any corrections, with the exception of the final sentence.