Timing the Market

We all know that market timing is bad and does not work in the long term. But can we eliminate it completely? I don't think it is possible though. I have just come to realize how difficult it is to try NOT to time the market.
Currently, I have around $10,000 in my Questrade trading account. I plan to use the money to balance my ETF portfolio that I have set up by following the couch potato approach. But I have not done it yet. Every time, when I saw the market went up, I said to myself,"Um, it might go down tomorrow. I probably should not be buying today. I should just wait." Then, it did go down the next day. Did I pull the trigger? No, I did not because I am afraid it might go down further.
The similar thing could happen when you try to sell. People keeps post ponding the selling because they always want to sell for more. Fear and greedy are really the worst two enemies of individual investors. We can only not to time the market when we have overcome them.
Um......Should I balance my portfolio today?