成语 or expression for perservering I am looking for an expression (maybe a 成语) which can describe the idea of, "I know I have a long way to go, but if I keep trying, I can succeed." 

For example, "我的发音还差得远，可是"  Meaning, "My pronunciation has a long way to go, but I will keep working hard at it."  

I have found this one expression that seems to express it, is it appropriate? 

只要功夫深，铁杵磨成针

Or perhaps:

磨杵作针

Please let me know how I can best express this idea in a way that the average speaker can understand.
只要功夫深，铁杵磨成针 is good, and also:

坚持不懈
锲而不舍
水滴石穿
百炼成钢
熟能生巧
精卫填海
卧薪尝胆
有志竟成