Use parentheses to capture it. If you don't want to capture the minutes, don't use capturing parentheses:

  /(\d{1,2})(?=\s(?:mins|minutes))/
#  ^       ^      ~~
#  |       |        \
#  \ capture         don't capture
[download]

Thank you! Posting the solution that worked (returns 5) for me.

my $body_text="there are 5 minutes left in the program";

if ($body_text=~m/(\d{1,2})(?=\smins|\sminutes)/g) {
    print "here: " . $1 . "\n";
}
[download]

@Choroba: Another unusual thing happens if I run the code 2x in a row. The first if{} works but the second does not. Does the regex somehow need to reset?<\p>

my $body_text="there are 5 minutes left in the program";

if ($body_text=~m/(\d{1,2})(?=\smins|\sminutes)/g) {
    print "1st try: " . $1 . "\n";
}

if ($body_text=~m/(\d{1,2})(?=\smins|\sminutes)/g) {
    print "2nd try: " . $1 . "\n";
}
[download]

That's because of the /g, it remembers where the match happend last time and tries to match again after it.
map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]

To illustrate the effect noted in choroba's reply try the following:

use strict;
use warnings;

my $body_text="5 minutes left. Wait 6 minutes before nagging again.";

if ($body_text=~m/(\d{1,2})(?=\smins|\sminutes)/g) {
    print "1st try: " . $1 . "\n";
}

if ($body_text=~m/(\d{1,2})(?=\smins|\sminutes)/g) {
    print "2nd try: " . $1 . "\n";
}
[download]

Prints:

1st try: 5
2nd try: 6
[download]

Optimising for fewest key strokes only makes sense transmitting to Pluto or beyond

Another example of the effect of what you were doing in the OP (i.e., a non-zero-width capture within a zero-width assertion):

Win8 Strawberry 5.8.9.5 (32)  Wed 11/11/2020 18:02:18
C:\@Work\Perl\monks
>perl -Mstrict -Mwarnings -l
my $s = 'ABCDE';

while ($s =~ m{ (?= (\w+)) }xmsg) { print $1; };

^Z
ABCDE
BCDE
CDE
DE
E
[download]

Update: This might be a better example of overlapping capture:

Win8 Strawberry 5.8.9.5 (32)  Wed 11/11/2020 21:41:12
C:\@Work\Perl\monks
>perl -Mstrict -Mwarnings -l
my $s = 'ABCDE X YZ FGHI';

while ($s =~ m{ (?= (\w{3})) }xmsg) { print "'$1'"; };

^Z
'ABC'
'BCD'
'CDE'
'FGH'
'GHI'
[download]

Quibble: this is actually a lookahead, not a lookbehind. A lookbehind would be

Note that, depending on the version of Perl in use, variable-length lookbehinds (e.g. m/(?<=\bare\s{1,3})(\d{1,2})/ are either unavailable, or restricted in how much they can match.

Variable-length positive lookbehinds of any length can be realized with the \K regex operator introduced with Perl version 5.10; see Lookaround Assertions in perlre. (Update: I should add that \K is mainly useful in s/// substitutions.)

---

Give a man a fish:  <%-{-{-{-<