Good morning, @antonieta71, Babysteps. Little changes daily will be your key to moving to a more positive frame of mind. It takes repetition to change old habits so don’t expect changes overnight. But don’t give up, you can do this! ☺️ You have control over your effort and your attitude.

I have a quote that’s taped to my bathroom mirror and I read it every day, though I know it by heart. I’ve had the original copy for almost 40 years! It became the motivating factor in my life since the very first time I read it.
“I, not events, have the power to make me happy or unhappy today. I can choose which it will be. Yesterday is dead, tomorrow hasn’t arrived yet. I have just one day, today, and I’m going to be happy in it!” Groucho Marx

Mayo Clinic has a really great page on Healthy lifestyle and stress management. Start with this page and then take a look online for other sites dedicated to positive thinking. There are videos on youtube to help with mindfulness exercises and also motivational videos. All of a sudden, just the right thing will resonate with you like the Groucho Marx quote did with me.
https://www.mayoclinic.org/healthy-lifestyle/stress-management/in-depth/positive-thinking/art-20043950

Being postivie doesn’t mean you never have a negative thought. It just means you don’t let those thoughts control your life.
What positive things have impacted you today so far?