Don’t start believing
What do you believe in? More specifically, do you need to believe in something in order to live a good life?
Let’s say you believe exercising regularly is good for your health, which has clear scientific evidence behind it. But whether you believe it or not doesn’t change the fact it’s good for your health. You either exercise regularly and get the health benefits, or you don’t exercise and do not get the benefits. So why does it matter if you believe exercising regularly is good for your health or not?
The obvious answer is if you don’t believe it you won’t do it (or vice versa), but is that really true? Most people who binge drink believe it is bad for their health, but they still do it regardless; most people who speed on a highway believe that could result an accident or at least impose a higher risk of hurting themselves and others; most people believe reading (books) is valuable to their learning but only a few read books consistently. Should I go on?
The next answer may be that, if you believe something, it makes doing / following this thing more enjoyable. That seems to be true on the surface: if you believe the health benefits of exercising then it makes it easier for you to work out, whereas if you are still skeptical about it, you may feel a lot more resistance when the pain comes… Does this mean it’s the belief that what you are doing is good makes the activity more enjoyable? Sure, feelings are subjective and it could be very much so for some people believing in what they are doing augments their experiences. Given the risk-avert nature of humans, a more interesting question is - does not believing what you are doing makes the activity less enjoyable?
I think you can pretty much guess where I’m going from this point - if the answer to the last question is yes, meaning not believing it makes whatever you are doing less enjoyable, then a rational person  should always believe whatever they are doing, to optimize their experience doing it. However, we are faced with an assumption that human belief systems can be easily tricked and adapted per one's will  - that sounds pretty counterintuitive if you have been following anything that goes on in the world today.
So why hasn’t evolution allowed us to simply manipulate our brain to believe something on-demand? With all the incredible benefits emerged from billions of years of evolution, it seems plausible one mutated gene that could flip switches in our brain would have been preserved through natural selections, if it indeed turned out to optimize human experiences.
So does that mean believing something has no positive correlation with the enjoyment of the experience itself? I think so. The activity itself will eventually uncover its level of joy, or sadness, to you, based on all the new information that you have gathered throughout the experience. You don’t need to believe in the health benefits of exercising to notice that you have since lost a few pounds and feel more energetic throughout the day; you don’t need to believe in reading books until you can fix a new wooden table because you read “carpentry for dummies”; you don’t need to believe binge drinking is bad to end up in a hospital with tubes out of your stomach.
What is all this mumbo jumbo about? Well, I believe we don’t need to believe anything, and we shouldn’t believe anything, in order to live a good life. Beliefs do not add value to our experiences in life, but create sufferings outside the underlying activity. Believing in exercising is good for your health induces anxiety when you are not “exercising enough”; believing reading is good for your learning turns into guilt when you haven’t read a book for a month. But what happens when you believe nothing ? Does that mean you would speed on the highway if you didn’t before? Does that mean you would binge drink to death even if you were a teetotaler before? I don’t think so. You didn’t speed on the highway because it wasn’t an enjoyable experience to you, and it will continue to be a non-enjoyable experience to you. You didn’t drink because drinking wasn’t something you enjoyed, and you aren’t about to suddenly like the bitterness of beer and the next-day hangovers.
Let life show you what you like, and not like. Observe. Don’t start believing.
 Broadly defined in this context as someone who maximizes their well-being or “happiness” in life
 In theory, an alternative conclusion is that humans believe in anything and everything all the time to maximize their chance of not losing on optimal experiences; but this doesn't happen, does it?
 Yes one can argue believing nothing is still believing something. Let's call it a meta-belief and exclude these meta-beliefs in the subsequent discussion.