Through the power of Christ in his life, Paul has been able to endure everything he has gone through, and he has been content in all his circumstances:
10 I rejoiced in the Lord greatly that now at length you have revived your concern for me. You were indeed concerned for me, but you had no opportunity.11 Not that I am speaking of being in need, for I have learned in whatever situation I am to be content.12 I know how to be brought low, and I know how to abound. In any and every circumstance, I have learned the secret of facing plenty and hunger, abundance and need.13 I can do all things through him who strengthens me.”
Finally, even without the other contexts, within the verse is a principle overlooked many times – “through him [Christ] who strengthens me.” Before someone can take this verse and use it as a spiritual steroid, it must be remembered that the power lies not with us but with Jesus Christ. If we are living our lives in our own power and neglecting our time with him, can Philippians 4:13 really have its full meaning?