天気が暑かった（天気が暑かった→ You usually just say "暑かった". When you describe the weather, you use adjectives such as "良かった" and "悪かった".）ですけど（ですけど→ You usually don't repeat "です" in this sentence. You just say "けど" in the former part of the sentence.）人は多かったです。／そこでバドミントンをしました。／考えたことより（考えたことより→ I guess you mean "than I had expected". If so, you say "思ったより".）大変な運動でした。／でも、あせもなって（なって→かいて. "あせをかく" is a standard expression to mean "sweat".）、面白かったのでいい運動だと思いました。〔"ので" is a conjunctive particle with which you combine two things when there is a causal relationship between them. In this sentence, however, there is no such between "面白かった" and "いい運動". I would change the order of the phrases and say "面白かったし、あせをかいたのでいい運動だと思いました", the latter half of which is a commonly-used expression.〕

平日は普通、仕事が終わった後で主人（主人→ Some people think you had better not call your husband this way because this is a word what a servant calls his or her master. You might as well say "夫".）とジムに行きます。／でも今週はジムもやすみなので店開きをしません（店開きをしません→ A gymnasium is not a store. So, you usually don't use a word "店" to describe it. You just say "開いていません"）。／それで代わりに家の近くにある公園で（で→ "公園" in this sentence is a destination you went to. In this case, you use a particle "に" or "へ".）行ってきました。／