python regex, How to match everything except headings?

I have this piece of text:

> 2. Shifting Your Mindset: Transforming your mindset from a negative or limited mindset to a positive one requires conscious effort and
> practice. Here are some key strategies to help you make that shift
>
> a. Self-Awareness: Start by becoming aware of your thoughts and inner
> dialogue. Notice any negative self-talk or limiting beliefs that may
> be holding you back financially.
>
> b. Reframing: Challenge and reframe negative thoughts or situations
> into positive ones. Instead of dwelling on financial setbacks, focus
> on the lessons learned and the potential opportunities they may
> present.

I want to match everything except the headings started with a number or a letter and followed by a dot(.), so the output should be:

> Transforming your mindset from a negative or limited mindset to a positive one requires conscious effort and
> practice. Here are some key strategies to help you make that shift:
>
> Start by becoming aware of your thoughts and inner
> dialogue. Notice any negative self-talk or limiting beliefs that may
> be holding you back financially.
>
> Challenge and reframe negative thoughts or situations
> into positive ones. Instead of dwelling on financial setbacks, focus
> on the lessons learned and the potential opportunities they may
> present.

So I tried this pattern: (?!\s*[a-z]\.\s.*:)(?!\d+\.\s*.*:).*
but I couldn't match them.

If you use re.sub you can focus on the parts that you don't want in the output.

I'll use these characteristics of what constitutes a "header":

• Starts with at the start of a line (possibly after some white space)
• Its first character is alphanumeric
• It ends with a colon, no further than 30 characters from the first (non space) character, potentially followed by some white space.

import re

s = """Shifting Your Mindset: Transforming your mindset from a negative or limited mindset to a positive one requires conscious effort and practice. Here are some key strategies to help you make that shift:
a. Self-Awareness: Start by becoming aware of your thoughts and inner dialogue. Notice any negative self-talk or limiting beliefs that may be holding you back financially.

b. Reframing: Challenge and reframe negative thoughts or situations into positive ones. Instead of dwelling on financial setbacks, focus on the lessons learned and the potential opportunities they may present."""

s = re.sub(r"^ *\w[^\r\n:]{0,30}:\s*", "", s, flags=re.M)
print(s)

This outputs:

Transforming your mindset from a negative or limited mindset to a positive one requires conscious effort and practice. Here are some key strategies to help you make that shift:
Start by becoming aware of your thoughts and inner dialogue. Notice any negative self-talk or limiting beliefs that may be holding you back financially.

Challenge and reframe negative thoughts or situations into positive ones. Instead of dwelling on financial setbacks, focus on the lessons learned and the potential opportunities they may present.

Thank you all for your feedback, however, I read the re documentation and finally I got the perfect answer which is this pattern:

(?<=:)\s*.*

this regex uses the lookbehind assertion will perfectly exclude every string that comes after a colon followed by 0 or more white spaces, which means, it will match all content paragraphs.