Firstly a construction with をあります is ungrammatical since ある is an intransitive verb, and を marks the direct object of a transitive verb (Note: を can also be used with intransitive verbs of motion, but ある isn't one of those).
Here are some examples from Weblio日本語例文用例辞書 of uses of 怠惰
彼女は私の怠惰を叱った。
She scolded my laziness
怠惰に過ごした。
I lazed around. (literally: [unnamed subject] spent time lazily)
私は怠惰すぎる。
I'm too lazy.
怠惰な学生
a lazy student
That's just a sampling of the shorter ones, but it gives a feel for various ways 怠惰 is used. None of those included ある, though it doesn't rule a sentence that uses ある out as impossible.
Oh, as for responding to 元気ですか, I would say 怠惰 not going to be natural.
To capture that feeling, you might say 元気じゃない, or だるい, or やる気がない
Others might have other suggestions as well.
Usage of 怠惰
I was wondering if you could casually use 怠惰 in a sentence like ”私はほんとうに怠惰をあります。” or would you have to use a different word for lazy or tired if some where to ask "元気ですか。"?