It's easy for me to stay focused on my purpose in life because my career totally encompasses it, even down to the part about expressing my love.
The tricky part is to stay focused on my priorities (and to keep refining them) so I won't let the lesser things distract me or consume too much of my time.
Another challenge is overworking. Simply because I'm so passionate about my work (and I feel I'm living my life purpose) and because my work is so enjoyable, I can definitely behave like a workaholic.
When I think back to the times before I was so clear about my purpose in life, this feels like a better set of problems to have.
(Though I hasten to add that I'm not advocating workaholism for anybody. I'm working on balancing myself in that area.)
Here's my life purpose that I posted on another question: