Being an SEO professional is a stressful job. It doesn't matter if you work for an SEO agency, yourself or of you work in-house for an organization, you'll find yourself anxious much of the time mainly because SEO is an inexact science.
The main reason SEO is a nerve-wracking profession is the time it takes to see results. Clients often have to pay for your services for six months before seeing results. While you can try to set their expectations upfront, they expect to see something for their money.
Google also frequently changes their algorithm. As an SEO professional, you have to stay up-to-date with the changes. A client can get hit by a change and you have to scramble to fix their site and help them get their rank back. Rankings also fluctuate because of unannounced CORE updates, but clients don't understand this.
Being an SEO professional is stressful because you can't guarantee results. You have no control over what Google does or what the competition does. A competitor could pay for 20 very high quality articles and outrank your client in a few months. The client is mad, but what can you do? You can explain to the client that paying for one blog post a week isn't enough, but it's hard to make them understand that their content, which they wrote, isn't good enough.
It's also nerve-wracking to audit a new client's website and find poorly done SEO. If they don't understand SEO, they won't know why you have to do extra work to correct their previous agency's mistakes.
You can spend hours of unpaid time educating clients about SEO. You'll have to explain the items in your contract, such as alt tag optimization, and why each one is important. Unfortunately, some clients will never sign on the dotted line and you've wasted time teaching a mini SEO class to someone who is just shopping for the lowest-priced SEO. For more information click here https://www.reddit.com/r/SEO/comments/dxg7qc/howhighanxietycanharmyourseocampaignsand/.