It is only through the conscious practice of time-management, and prioritizing the activities that are important to you, that you will achieve a solid academic/life balance.
Take time at the end of each semester to ask yourself, "What worked for me, and what didn't?" Then, to help keep your priorities in check without becoming overextended, cut low-value activities, only continue with ones that make you happy, and make finding time for yourself a priority.
The small effort spent reflecting and making a commitment to yourself is worth the big payoff in increased productivity, stress reduction, and overall happiness.