Something that is so wonderful about this and many like Scriptures, is that the Lord never puts qualifiers on His promises. Jesus simply states here that whatever you sow will indeed be returned to you in greater measure (that's the "running over" part). The world has stolen this saying from Jesus and attributed some fancy, religious, new-agey term "karma" to describe this spiritual principle. God thought of it first. It isn't some universalist theory that we all hope will happen to bad people; it is a real spiritual law. And it works.
The question to all of us as believers is,"do we trust the Lord's principles?" If we did, we would stop at nothing to sow as much of ourselves into the kingdom of God and His people. Take a look at Galatians 6:7-10:
Do not be deceived, God is not mocked; for whatever a man sows, that he will also reap. For he who sows to his flesh will of the flesh reap corruption, but he who sows to the Spirit will of the Spirit reap everlasting life. And let us not grow weary while doing good, for in due season we shall reap if we do not lose heart. Therefore, as we have opportunity, let us do good to all, especially to those who are of the household of faith (NKJV)
Again, God does not put any qualifiers on His Blessing. He simply says "whatever;" whatever you sow in life you will receive back. If you sow finances, you will reap finances. If you sow friendship, you will receive friendship. If you are a jerk, you will reap... unpleasantness, to say the least. Whatever you may need in life can be obtained through the spiritual principle of sowing and reaping. It is the way God operates, and we are made in His image. He made us to need each other, and while there is an added emphasis on investing in the Body of Christ, it is God's desire that we invest ourselves into all people.
We often operate under the assumption that we need to have others pour into us before we can give anything of ourselves. But think on this for a moment: if each member of the Body invested themselves fully into each other, then even though you are pouring out everything you have, you would have many others pouring themselves into you. Think of it financially (yes, the "prosperity preacher" strikes again), if we all took God's Word regarding our finances seriously, and gave all that we could to the kingdom of God, our churches would not be in the financial trouble they are in now. We would not be holding "garage sales" to fund our missions programs. Honestly, do you think that is how God wants to fund His Kingdom?? Jesus commissioned us to reach the world with His Gospel, and you think He cannot come up with a better means of financing the operation than having the church rummage through each others junk? If we all took God at His Word, gave to our fullest abilities (even if all we have is a "widow's mite"), and believed His promises, we would all receive "many times as much at this time and in the age to come, eternal life" (Luke 18:30).
This is but a taste of something the Lord has shown me this past weekend. It is a little rough, I know. I will work on it some more throughout the week. I wanted to make sure that I got it "on paper" before I forgot it. Just understand that the more you invest into God and His people, the greater the return you will have in this lifetime. Stop operating under the assumption that everything is spiritual. Of course, Jesus told us to store up treasures in heaven, but He also gave us promises for how to live an abundant life here on the earth, as well. Judging by the way things are going, we all need it.