It is common in the Bible for people to "rise up," and it would be easy to pass over the phrase as simply describing a physical action. But in fact it represents an elevation in spiritual state, moving to a more internal frame of mind closer to the Lord. Often it has to do with understanding a new or important idea; we "rise up" to a state of greater perception and enlightenment. Obviously context is crucial to the exact meaning of the phrase in a given passage -- it matters greatly who it is that is rising up, and why.

8418. 'And gather the thing of a day in its day' means continually, in proportion to need. This is clear from the meaning of 'gathering' as receiving, for when 'raining' means flowing in - that is to say, good from the Divine flowing in - 'gathering' means receiving, because the one activity goes with the other; from the meaning of 'the thing' as the object to which it refers, in this instance the bread or manna from heaven; and from the meaning of 'a day in its day' as continually, in proportion to need. Continually is meant because they received the manna daily (for the meaning of 'daily' is continually, see 2838); and in proportion to need is meant because they were to gather as much each day as they were going to need and no more, which for each person was an omen