Our Scripture reading today is Psalm 27:14, "Wait on the LORD: be of good courage, and he shall strengthen thine heart: wait, I say, on the LORD."
The strength of heart that we all need follows our faithful waiting on the LORD.  The picture we should have of waiting on the LORD is one of service for the LORD.  We can be waiting on the LORD in prayer and praise.  We can be waiting on the LORD by looking for ways to serve others.  Waiting on the LORD is not necessarily standing still or sitting on the sidelines.  
Our walk with the LORD is also a part of waiting on Him.  The closer we get to Him, the more clearly we will hear His instructions for the day.  It matters not how many years we have been saved, we need His strength in order to function day by day.  The promise is clear in this verse.  If we wait on the LORD, He will provide the strength we need.  His strength is made perfect in our weakness.