Paul was a veteran soldier in the faith and he's writing and encouraging a fresh new recruit. Like any new recruit, Timothy might be having some second thoughts about following Jesus, but here Paul gives a great dose of truth. There will be suffering, but when he writes "as a good soldier of Christ Jesus" it echoes the encouraging words of "well done, good and faithful servant." We all know this...that following Jesus we should expect suffering to come our way.
Paul also tells us what a good soldier is all about, "no soldier gets tangled in civilian pursuits." One of my favorite Disney movies is "Tangled", which most of you probably watched. One thing that kept coming to mind was the fact that with that much hair it would have gotten caught on so many things. This is the same image we get from the Bible. When Paul uses the word "entangled" the word is used in another part of the Bible where sheep get caught by their wool on a thorn bush and get stuck.
When I look at my life I need to ask myself what are my distractions, what am I getting stuck on, and what is sucking my energy away because I'm stuck? We have so many distractions don't we? Jesus knew how busy you were going to be when he created you. The key, I think, is to constantly keep your eyes on your commander, Jesus. Getting untangled is sometimes part of the mission itself...it's where we become more like Jesus and we turn away from the things that "entangle" us from pleasing the one who enlisted us.