In the end, good time management comes down to self-discipline. Without this you can become prone to procrastination. Let's face it, there is nearly always something you want to do more than your university work. If you are working on a particularly difficult or uninspiring piece of work then even jobs you hate suddenly look appealing.
Self-discipline is all about balance. You need to build some me-time into your routine so that you do not feel like your life is all work and no play. This can be checking your social media at specific times a day; a daily work-out routine; spending time with family or a couple of hours watching TV* or gaming* at the end of the day. When this is planned, it is easier to convince yourself to spend other times on your university work.
*Gaming and watching TV (especially with full series available) are known time-sponges. You can start off thinking 'I'll just have a half-hour break" and end up still doing it hours later. If you are reasonably disciplined and merely forget the time, then always set a timer on your phone or watch to remind you to get back to work. If it is more problematic than that, then don't start this activity until you have finished working for the day. Consider it your well-deserved reward.