I have a well paying job, kids, wife, and a mortgage. However, I got an idea that is not big, not hard, totally doable. I'm interested in the start up as a hobby but see it as potentially a long term viable business venture. Yes, I know most start ups "fail." But that's open to interpretation. What does it mean to fail? (i.e. failure to move beyond the idea?) hmm. With that said, I'm looking at a total blank slate with nothing more than token technical skills, above average business intuition, and a wife that will remind me everything is great as it is right now.
Firstly you should be talking to her and not a random startup community about this. She probably knows best about what will get her onboard.
Also, you can always start it as a side project and only go "all in" if it passes a certain level of success. This takes the paying job and mortgage out of the equation and just requires your wife to be supportive with the time you are spending on it.
As for "most startups fail", I really find that such a ridiculous statement, likewise the statistics like 1 in 10 fail. How many startups are attempted by people that can't commit the appropriate time or money? How many are attempted by people with no technical skills? I would be much more interested to see "1 in 2 startups fail when you have appropriate time, capital and expertise for the venture you are attempting". I don't believe it's a lottery, do the right things and you have a very good chance of success.
Obviously the first thing you have to do is talk to your wife about it. She's the only one that can truly tell you.
Three things to consider:
Lastly, take a look at these related threads:
You starting a business represents a great risk to you and your wife. If you have a comfortable life as it is, why should she want to risk giving that up? Most people (fairly) don't want to take on that risk - that's why most people are employees and not entrepreneurs.
Your wife should be happy with your decision if she understands how it benefits both of you - if it's something that you need to do, and if you can be committed to the project in a way that doesn't cost your livelihood, she should be able to accept that easily.
However, if your commitment to the startup includes a significant risk that you would have to downsize your lifestyle in the medium-term, that may obviously be unattractive. There are other, related risks - if there's a risk you'll have to spend 100 hours a week working on your own business (or, on a combination of your existing job and your business) to ensure any level of success, that will impact significantly on your family life.
Your wife might have some valid concerns - you'll have to talk to her clearly about your plans, convince her that it will be a worthwhile investment (for you, and her too!), and be willing to accept her point of view.