Both of the sentences 'Spending my Sunday at home' and 'spend my Sunday at home' are correct depending on their context of use, and tense.

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Family is one of the most important things you will ever have. Make it a point to spend time together, even if it is just to watch a movie and eat popcorn on the weekend. Try to do different things each month together, like going bike riding or having a picnic outside.

Spending a lot of time on your knees can cause pain after a while. Answer: spend less time on your knees.

The future tense of "spend" is "will spend" or "going to spend."