This is a mental problem.

Don't play stakes which you do not have plenty bankroll.
Focus on making correct decisions, not the result.

Hey ronneycui!
I think you should know beforehand that many of the players you will be facing are doing this for a living so what you should ask yourself is : Am I doing this to make money and create a sustainable income or am I doing this as a hobby and I enjoy the game?
Sometimes I play hockey with friends and I gamble, sometimes its nintendo and sometimes its just something stupid like chugging a beer, I know that im not going to win at all these games but i enjoy doing them and sometimes lose money. I think this somewhat applies to poker, if its a hobby, youre doing it at a reasonable rate, its not affecting your work or social life and you can afford to lose or win the amounts you are gambling then its fine.
If you are thinking about doing this for a living, you better get to work! Studying hard, setting up a work plan, playing lower and within your bankroll, expecting some swings that you can handle mentally and so many other things that would take me quite some time to enumerate...
After all that said, remember why we all started to play this game, competitive nature, thrill of victory and winning/losing at a game we love to play!

If you are afraid of losing, play as low as possible. Preferable at 2NL and try to study the game as much as possible.

i have similar problem iam not afraid of loosing money but iam afraid then when i win big in like 30 minutes then i make one mistake and i get little tilt and lost motivation in this day then i just cant play.

Play PLO. Problem solved.

Try to understand that as in life, loosing is part of poker. It's what we do with those losses that matter. No one that plays has a perfectly linear profit line. We will even loose a percent of the time with the exact same hand that we win with. Use those losses that you incur as a challenge to better your self and your performance at the table next time you sit. Weither it be to control your anxiety of loosing a hand and potentially using that as a life lesson, or learning how to play a hand differently so that you will loose with that hand less often, which in turn builds your confidence because you've gained a new skill. Learn more about the game and yourself by understanding that loss is inevitable but that it doesn't have to be final.

Build on the concept of self within the game of poker by finding out why you are so worry about loosing. Maybe I'm reading too far into it (I got a meditation tool for Christmas so i'm all existential now lol) but if it was about the money I don't think you'd be thinking about playing poker for money in the first place. Life is full of risk and with that risk there will be loss. That doesn't mean you've failed, only that you're not there yet.

Great community we got here! And ronneycui, its 10$/month for a very valuable subscription at RIO, dunno if you have it already, but i think its really worth it!