I think exercising is a great way to relieve stress.
to relieve stress は「[ストレス](https://eikaiwa.dmm.com/uknow/questions/46001/)を緩和・[解消](https://eikaiwa.dmm.com/uknow/questions/66793/)する」。
他にも、to get rid of stress(ストレスを取り除く)、to reduce stress(ストレスを軽減する)などの言い方もできます。
「ストレスがたまる」は to feel stressed, to get stressed, to be stressed などが使えます。
I exercise when I feel stressed.
(ストレスがたまった時は運動する。)
Exercising is a good way to help relieve/reduce stress.
You can use either 'relieve' or 'reduce' when using this expression as both have similar meanings in this context.
*relieve= o make an unpleasant feeling, such as stress, less strong
Exercising is one of the best ways to reduce stress.
1)「本当に良いと思う」という部分をI believeで表現してみました。believeを使うことで「本当に」の部分が伝わると思います。「ストレス解消」の部分は、「ストレスとうまく付き合う」という意味として捉えて、stress managementで表現できると思います。help(s)は「役立つ」です。
2)one of the best waysを直訳すると「良い方法の一つ」となります。日本語では「ベスト」なものは「ひとつ」という考え方がありますが、英語では、「ベストなものがいくつかあってその中のひとつ」という発想をする傾向にあります。reduce stressは「ストレスを減らす」です。
参考になれば幸いです。
If I feel stressed, I let it all out through exercising
If you wish to describe that exercising is good for stress, in your opinion, then you may use the first example sentence (which is a general expression), or the second example sentence (which is a more personal example).
Many people use exercise as a way to release stress.
The first example is something I would use as a statement, especially if it is something I strongly believe. When someone as you why you exercise, I would use answer number two. And the third response is another generic statement, but it implies that there are many people that share this perception of exercise with regards to stress.
Personally,I think that a good way to relieve stress is to exercise.
"Personally, I think that a good way to relieve stress is to exercise."
To relieve something to to get rid of eliminate a feeling or an object. In fact there are numerous synonyms of how to reduce stress.
"Personally, I think that a good way to relieve stress is to exercise."(個人的には、運動でストレスを解消するのがいいと思う)
"To relieve something" は「〔物・感情を〕取り除く」という意味です。「ストレスを和らげる」にはいろいろな言い方があります。