Realistic expectations - the vast majority of day traders never become consistently profitable, but then again, any idiot with a phone can be a day trader from Robinhood so that’s a big group you need to be in the top ~few% of to succeed.
Stable/even temperament - to deal with psychological stresses. Being worried about losing money when it’s happening detracts from your performance. Better is to have sized your bet so you don’t lose enough when you cut your losses to have caused that level of anxiety in the first place. Know yourself and find a trading style that suits you. There are millions of ways to make money in the markets, but not all will go well for any given person.
Patience - no called strikes in investing or trading. If you don’t see anything good, just wait and don’t feel compelled to act. There are costs to trading, even if the modern brokerage model tries to hide them (spreads).
Hard work, not “secrets” - the people that succeed work hard, more than a full time job, just on improving and researching their trades. Attention to detail is often very important. A part time commitment is quite unlikely to succeed. I’ve seen many traders come and go, and ones who succeed are the ones who can’t imagine doing anything else and might be bored on the weekends waiting for the markets to open again on Monday.
If it’s working, scale it up. If it’s not working, stop or scale it down until you can fix it or figure out why.
People won’t believe you online if you claim to succeed at trading, either out of envy or ignorance or skepticism. That’s ok, you don’t need them to believe you and it’s probably a waste of time trying to convince them. The proof is in your brokerage balance and you can spend that.