Thinking itself is not a bad or unhealthy activity but thinking too much can be reason of feeling stress and anxious. Thinking over and over again about the same idea can effect on your mantel ability.
So give you mind a break and stop think too much
Write your ideas and say out loud:
When you think about any idea write down the thing that comes on your mind, when you complete writing now say out all these ideas loudly. By saying your ideas loud you will feel the power from inside.
Ask for advice:
Instead thinking too much about the similar idea over and over again you ought to ask for advice to a sincere buddy.
Living in the Moment:
Stop your mind to strolling here and there and start living in the moment can help you a lot to stop thinking about the things that passed away or the things that will never happen in the future.
Mostly our thoughts attack on us when we are all alone. Your social circle can be helpful in your way to feel lees stress.
Whenever I feel concerned, I love to go a park or a riverbank as nature has huge power to console and relax the human being.
Get a new hobby:
A new and healthy hobby can give your mind a new energy and by doing your favorite work you will feel more relaxed and calm.
Set a “thinking time” aside for yourself every day:
Set a time for thinking because thinking it self is a healthy activity. By setting a time for thinking you giving your mind the message that it have to stop thinking all the time.