I can do all things through Christ which strengthens me.
Since God is always in charge, he can make anything happen. If he wants me to speak French and the Holy Spirit comes upon me, I can do it. If he wants me to fly and I have instructions from him to do so, I will fly.
However, that really is not what this verse means. It is best to check the verses before and after to get a better understanding of how he set the example so that we too can do all things through Christ.
Keep in mind that this was written by the Apostle Paul who was thoroughly sold out to Christ. He wrote this letter while being imprisoned in Rome by the command of the vicious, heartless Nero. Likely Paul wrote these words while he was under duress.
In verse 11 he said that whatever situation came upon him he learned to be content. In verse 12 he explained that his past experiences included such words as being abased and suffering.
In verse 15 he shared his disappointment with churches, other than the Philippians, who expressed no concern about his well-being. Only the Philippians reached out to him. In verse 19, he said, “but my God shall supply all your need according to his riches in glory by Christ Jesus.”
How remarkable was this man who experienced so much for Christ! In 2:14 he said, “do all things without murmuring and disputing.” This is sound advice for today’s church members.
In other Scriptures Paul said that he endured attempts to murder him, he was stoned, shipwrecked on more than one occasion, he was beaten several times, he suffered hunger, homelessness, heartache, snakebite, was betrayal by former friends and church members, he was mocked, his authority as a leader was challenged, he was forced to do manual labor solely that he might have something to sustain his life, he disputed with those possessed of evil, and had a personal affliction he called a thorn in his side, he knew misery, and so much more.
With his history he declared that he could do anything under the terrible circumstances of his life because it was Christ with him and who would give him the strength to endure.
We had no inkling that the circumstances in which we now live would come upon us, but in faith can endure and conquer. Christ strengthens those who know him and have had their souls born again through his blood that he shed on the cross.
All those who are in the family of God have an advantage over the circumstances of this life whatever they may be. This is not because of our own strength, but Christ who strengthens us!