The sentiments expressed Ruel’s “Hard Sometimes” are premised on the emotional discomfort the singer feels due to being away from home for a long period of time. They are very-personal in relation to what Ruel has actually been going through in his recent rise to superstardom, which requires him to be on the road often.
And basically, what he is saying is that being “far away from all (his) friends” is difficult a lot of time. Or another way of looking at it is that he’s homesick and lonely. Thus as the lyrics state, he makes a conscientious effort “to be happy”. But at the end of the day, it all comes back to him acknowledging that actually experiencing joy under such circumstances is “hard sometimes”. And that is where the song’s title comes from.