我很疲惫!
我很疲惫! 天气很热今天了. 我活动和我的同事室外了.
我很累(lei4)！今天天气很热，我和我的同事做了室外运动。
The way you wrote is very Engnese. LOL! Grammerically it's not very fluent in Chinese but at least you chose the correct words so it's not hard for me to guess what you mean.
Here are some problems:
1. Like English, in Chinese there are differeces between written and spoken Chinese. Take for example, the word 疲惫 does mean tired or exhausted but it's usually used in a formal way like in some articals or news. The other word 累 for tired is more comfortable in daily Chinese conversation.
2.The position of time is always at the very beginning of a sentence or behind the subjects. e.g. 今天我有中文课。 or 我今天有中文课。
3. Usually we put all subjects related to a certain action before the verb. It's like "I with my colleague exercise". And places are also put before the verbs and the structure is like "sb&sb + time + place + verb + object" . e.g. 我和朋友下午去动物园看熊猫。
我很疲惫!
我很疲惫!（我觉得“累”更口语化。。^_^) <em>今天</em>天气很热今天了. 我活动和我的同事室外了. 我和同事进行了室外活动。
What I meant: I am very tired. the weather was hot today and I exercised with my coworkers outside.
我很疲惫!
我很疲惫! 天气很热今天了. 我活动和我的同事室外了.
What I meant: I am very tired. the weather was hot today and I exercised with my coworkers outside.
我很累 今天天气很热 我和我同事在室外做了运动
我很疲惫!
我很疲惫! 天气很热今天了(今天天气很热，）. 我活动和我的同事室外了.（ 我和我的同事在室外活动了）
What I meant: I am very tired. the weather was hot today and I exercised with my coworkers outside.
我很疲惫!
我很疲惫! 天气很热今天了. 我活动和我的同事室外了.
→ 我很累!(比較口語)今天天氣很熱, 我和我的同事去戶外活動
What I meant: I am very tired. the weather was hot today and I exercised with my coworkers outside.
