This is a matter of style and word choice, so it is a matter of taste and not everyone will agree. In my opinion you don't "solve" a "hurdle." Literally, a hurdle is a low fence you must jump over. There is an Olympic competition called "the hurdles." Runners run, and have to keep jumping over low fences blocking their path. You can "solve" a problem, a puzzle, a riddle, or a difficulty. For a hurdle, appropriate verbs would be "overcome" and "surmount." "We need to overcome the hurdle instead of just complaining." If you are trying to be colorful, you can also use the verb "to hurdle," which means to leap over a hurdle, so it can mean to give a burst of intense effort. However, "to hurdle a hurdle" sounds bad. If we want to use the verb "to hurdle," we need to find a different noun. "We need to hurdle the obstacle," "We need to hurdle the barrier," "We need to hurdle the obstruction."

Don't use "so" as an interjection in formal writing. It could also be a coordinating conjunction, but that would make this into a dependent clause rather than a sentence. I would suggest: We need to do more to solve the problem besides just complaining. Instead of just complaining, we should do more to solve the problem.

It looks natural in compositions, however, for a slightly smoother flow, you could consider rephrasing it as: "Therefore, we need to take more action to overcome the hurdle instead of just complaining."

Thanks for all posed suggestions!