Stress
A life coach job can be extremely stressful considering you are self-employed. Your clients' fates and your own rests totally on your shoulders. Here are some stress factors:
You could give really bad advice to a client who is moderately successful and tank his career.
Your reputation is built on the success of your clients. If they go down, you go down.
You need to sound like you know what you're talking about all the time, even if you're having a bad day, you ate something bad the night before, or your dog died.
You could fail at your marketing efforts and not have enough clients to pay the rent.
So...yeah. Stressful. But so long as you are good at marketing yourself and give reasonably good advice, you should do alright.