As an NES, but not an English specialist:
1. I would personally use "rely" rather than "lean" in an inspirational context - "lean" has some negative overtones that "rely" doesn't.
2. I would rephrase as: "I believe personal networks and experience are the only proper routes to take in workplace.
You need to keep adding to your experience to make you stand out from the crowd."
Note that, in an inspirational context, "believe" is more powerful than "think".
Hope this helps
- For Teachers