Managing your stock investments doesn't have to be a daily pain. Rebalance once a year for stress-free investing. Making money on your investments can be intoxicating.
Think of your investment account more like a savings account. Put money in every month. At the end of every three or six months, use the money you've accumulated to buy more shares of the stocks.
I'm a buy-and-hold investor, but there may be rare occasions when you should sell a stock in your portfolio. The reasons are probably fewer than you think, and whether the stock fits your overall portfolio strategy.